20 files changed, 2258 insertions, 0 deletions

diff --git a/engine/add_party_mon.asm b/engine/add_party_mon.asm
new file mode 100644
index 00000000..b20913dd
--- /dev/null
+++ b/engine/add_party_mon.asm
@@ -0,0 +1,345 @@
+_AddPartyMon: ; f161 (3:7161)
+; Adds a new mon to the player's or enemy's party.
+; [wMonDataLocation] is used in an unusual way in this function.
+; If the lower nybble is 0, the mon is added to the player's party, else the enemy's.
+; If the entire value is 0, then the player is allowed to name the mon.
+	ld de, wPartyCount
+	ld a, [wMonDataLocation]
+	and $f
+	jr z, .next
+	ld de, wEnemyPartyCount
+.next
+	ld a, [de]
+	inc a
+	cp PARTY_LENGTH + 1
+	ret nc ; return if the party is already full
+	ld [de], a
+	ld a, [de]
+	ld [hNewPartyLength], a
+	add e
+	ld e, a
+	jr nc, .noCarry
+	inc d
+.noCarry
+	ld a, [wcf91]
+	ld [de], a ; write species of new mon in party list
+	inc de
+	ld a, $ff ; terminator
+	ld [de], a
+	ld hl, wPartyMonOT
+	ld a, [wMonDataLocation]
+	and $f
+	jr z, .next2
+	ld hl, wEnemyMonOT
+.next2
+	ld a, [hNewPartyLength]
+	dec a
+	call SkipFixedLengthTextEntries
+	ld d, h
+	ld e, l
+	ld hl, wPlayerName
+	ld bc, NAME_LENGTH
+	call CopyData
+	ld a, [wMonDataLocation]
+	and a
+	jr nz, .skipNaming
+	ld hl, wPartyMonNicks
+	ld a, [hNewPartyLength]
+	dec a
+	call SkipFixedLengthTextEntries
+	ld a, NAME_MON_SCREEN
+	ld [wNamingScreenType], a
+	predef AskName
+.skipNaming
+	ld hl, wPartyMons
+	ld a, [wMonDataLocation]
+	and $f
+	jr z, .next3
+	ld hl, wEnemyMons
+.next3
+	ld a, [hNewPartyLength]
+	dec a
+	ld bc, wPartyMon2 - wPartyMon1
+	call AddNTimes
+	ld e, l
+	ld d, h
+	push hl
+	ld a, [wcf91]
+	ld [wd0b5], a
+	call GetMonHeader
+	ld hl, wMonHeader
+	ld a, [hli]
+	ld [de], a ; species
+	inc de
+	pop hl
+	push hl
+	ld a, [wMonDataLocation]
+	and $f
+	ld a, $98     ; set enemy trainer mon IVs to fixed average values
+	ld b, $88
+	jr nz, .next4
+
+; If the mon is being added to the player's party, update the pokedex.
+	ld a, [wcf91]
+	ld [wd11e], a
+	push de
+	predef IndexToPokedex
+	pop de
+	ld a, [wd11e]
+	dec a
+	ld c, a
+	ld b, FLAG_TEST
+	ld hl, wPokedexOwned
+	call FlagAction
+	ld a, c ; whether the mon was already flagged as owned
+	ld [wUnusedD153], a ; not read
+	ld a, [wd11e]
+	dec a
+	ld c, a
+	ld b, FLAG_SET
+	push bc
+	call FlagAction
+	pop bc
+	ld hl, wPokedexSeen
+	call FlagAction
+
+	pop hl
+	push hl
+
+	ld a, [wIsInBattle]
+	and a ; is this a wild mon caught in battle?
+	jr nz, .copyEnemyMonData
+
+; Not wild.
+	call Random ; generate random IVs
+	ld b, a
+	call Random
+
+.next4
+	push bc
+	ld bc, wPartyMon1DVs - wPartyMon1
+	add hl, bc
+	pop bc
+	ld [hli], a
+	ld [hl], b         ; write IVs
+	ld bc, (wPartyMon1HPExp - 1) - (wPartyMon1DVs + 1)
+	add hl, bc
+	ld a, 1
+	ld c, a
+	xor a
+	ld b, a
+	call CalcStat      ; calc HP stat (set cur Hp to max HP)
+	ld a, [H_MULTIPLICAND+1]
+	ld [de], a
+	inc de
+	ld a, [H_MULTIPLICAND+2]
+	ld [de], a
+	inc de
+	xor a
+	ld [de], a         ; box level
+	inc de
+	ld [de], a         ; status ailments
+	inc de
+	jr .copyMonTypesAndMoves
+.copyEnemyMonData
+	ld bc, wEnemyMon1DVs - wEnemyMon1
+	add hl, bc
+	ld a, [wEnemyMonDVs] ; copy IVs from cur enemy mon
+	ld [hli], a
+	ld a, [wEnemyMonDVs + 1]
+	ld [hl], a
+	ld a, [wEnemyMonHP]    ; copy HP from cur enemy mon
+	ld [de], a
+	inc de
+	ld a, [wEnemyMonHP+1]
+	ld [de], a
+	inc de
+	xor a
+	ld [de], a                ; box level
+	inc de
+	ld a, [wEnemyMonStatus]   ; copy status ailments from cur enemy mon
+	ld [de], a
+	inc de
+.copyMonTypesAndMoves
+	ld hl, wMonHTypes
+	ld a, [hli]       ; type 1
+	ld [de], a
+	inc de
+	ld a, [hli]       ; type 2
+	ld [de], a
+	inc de
+	ld a, [hli]       ; catch rate (held item in gen 2)
+	ld [de], a
+	ld a, [wcf91]
+	cp KADABRA
+	jr nz, .skipGivingTwistedSpoon
+	ld a, $60 ; twistedspoon in gen 2
+	ld [de], a
+.skipGivingTwistedSpoon
+	ld hl, wMonHMoves
+	ld a, [hli]
+	inc de
+	push de
+	ld [de], a
+	ld a, [hli]
+	inc de
+	ld [de], a
+	ld a, [hli]
+	inc de
+	ld [de], a
+	ld a, [hli]
+	inc de
+	ld [de], a
+	push de
+	dec de
+	dec de
+	dec de
+	xor a
+	ld [wLearningMovesFromDayCare], a
+	predef WriteMonMoves
+	pop de
+	ld a, [wPlayerID]  ; set trainer ID to player ID
+	inc de
+	ld [de], a
+	ld a, [wPlayerID + 1]
+	inc de
+	ld [de], a
+	push de
+	ld a, [wCurEnemyLVL]
+	ld d, a
+	callab CalcExperience
+	pop de
+	inc de
+	ld a, [hExperience] ; write experience
+	ld [de], a
+	inc de
+	ld a, [hExperience + 1]
+	ld [de], a
+	inc de
+	ld a, [hExperience + 2]
+	ld [de], a
+	xor a
+	ld b, NUM_STATS * 2
+.writeEVsLoop              ; set all EVs to 0
+	inc de
+	ld [de], a
+	dec b
+	jr nz, .writeEVsLoop
+	inc de
+	inc de
+	pop hl
+	call AddPartyMon_WriteMovePP
+	inc de
+	ld a, [wCurEnemyLVL]
+	ld [de], a
+	inc de
+	ld a, [wIsInBattle]
+	dec a
+	jr nz, .calcFreshStats
+	ld hl, wEnemyMonMaxHP
+	ld bc, $a
+	call CopyData          ; copy stats of cur enemy mon
+	pop hl
+	jr .done
+.calcFreshStats
+	pop hl
+	ld bc, wPartyMon1HPExp - 1 - wPartyMon1
+	add hl, bc
+	ld b, $0
+	call CalcStats         ; calculate fresh set of stats
+.done
+	scf
+	ret
+
+LoadMovePPs: ; f2f9 (3:72f9)
+	call GetPredefRegisters
+	; fallthrough
+AddPartyMon_WriteMovePP: ; f2fc (3:72fc)
+	ld b, NUM_MOVES
+.pploop
+	ld a, [hli]     ; read move ID
+	and a
+	jr z, .empty
+	dec a
+	push hl
+	push de
+	push bc
+	ld hl, Moves
+	ld bc, MoveEnd - Moves
+	call AddNTimes
+	ld de, wcd6d
+	ld a, BANK(Moves)
+	call FarCopyData
+	pop bc
+	pop de
+	pop hl
+	ld a, [wcd6d + 5] ; PP is byte 5 of move data
+.empty
+	inc de
+	ld [de], a
+	dec b
+	jr nz, .pploop ; there are still moves to read
+	ret
+
+; adds enemy mon [wcf91] (at position [wWhichPokemon] in enemy list) to own party
+; used in the cable club trade center
+_AddEnemyMonToPlayerParty: ; f323 (3:7323)
+	ld hl, wPartyCount
+	ld a, [hl]
+	cp PARTY_LENGTH
+	scf
+	ret z            ; party full, return failure
+	inc a
+	ld [hl], a       ; add 1 to party members
+	ld c, a
+	ld b, $0
+	add hl, bc
+	ld a, [wcf91]
+	ld [hli], a      ; add mon as last list entry
+	ld [hl], $ff     ; write new sentinel
+	ld hl, wPartyMons
+	ld a, [wPartyCount]
+	dec a
+	ld bc, wPartyMon2 - wPartyMon1
+	call AddNTimes
+	ld e, l
+	ld d, h
+	ld hl, wLoadedMon
+	call CopyData    ; write new mon's data (from wLoadedMon)
+	ld hl, wPartyMonOT
+	ld a, [wPartyCount]
+	dec a
+	call SkipFixedLengthTextEntries
+	ld d, h
+	ld e, l
+	ld hl, wEnemyMonOT
+	ld a, [wWhichPokemon]
+	call SkipFixedLengthTextEntries
+	ld bc, NAME_LENGTH
+	call CopyData    ; write new mon's OT name (from an enemy mon)
+	ld hl, wPartyMonNicks
+	ld a, [wPartyCount]
+	dec a
+	call SkipFixedLengthTextEntries
+	ld d, h
+	ld e, l
+	ld hl, wEnemyMonNicks
+	ld a, [wWhichPokemon]
+	call SkipFixedLengthTextEntries
+	ld bc, NAME_LENGTH
+	call CopyData    ; write new mon's nickname (from an enemy mon)
+	ld a, [wcf91]
+	ld [wd11e], a
+	predef IndexToPokedex
+	ld a, [wd11e]
+	dec a
+	ld c, a
+	ld b, FLAG_SET
+	ld hl, wPokedexOwned
+	push bc
+	call FlagAction ; add to owned pokemon
+	pop bc
+	ld hl, wPokedexSeen
+	call FlagAction ; add to seen pokemon
+	and a
+	ret                  ; return success
\ No newline at end of file
diff --git a/engine/draw_badges.asm b/engine/draw_badges.asm
new file mode 100644
index 00000000..bd4aeaa8
--- /dev/null
+++ b/engine/draw_badges.asm
@@ -0,0 +1,120 @@
+DrawBadges: ; e880 (3:6880)
+; Draw 4x2 gym leader faces, with the faces replaced by
+; badges if they are owned. Used in the player status screen.
+
+; In Japanese versions, names are displayed above faces.
+; Instead of removing relevant code, the name graphics were erased.
+
+; Tile ids for face/badge graphics.
+	ld de, wBadgeOrFaceTiles
+	ld hl, .FaceBadgeTiles
+	ld bc, 8
+	call CopyData
+
+; Booleans for each badge.
+	ld hl, wTempObtainedBadgesBooleans
+	ld bc, 8
+	xor a
+	call FillMemory
+
+; Alter these based on owned badges.
+	ld de, wTempObtainedBadgesBooleans
+	ld hl, wBadgeOrFaceTiles
+	ld a, [wObtainedBadges]
+	ld b, a
+	ld c, 8
+.CheckBadge
+	srl b
+	jr nc, .NextBadge
+	ld a, [hl]
+	add 4 ; Badge graphics are after each face
+	ld [hl], a
+	ld a, 1
+	ld [de], a
+.NextBadge
+	inc hl
+	inc de
+	dec c
+	jr nz, .CheckBadge
+
+; Draw two rows of badges.
+	ld hl, wBadgeNumberTile
+	ld a, $d8 ; [1]
+	ld [hli], a
+	ld [hl], $60 ; First name
+
+	coord hl, 2, 11
+	ld de, wTempObtainedBadgesBooleans
+	call .DrawBadgeRow
+
+	coord hl, 2, 14
+	ld de, wTempObtainedBadgesBooleans + 4
+;	call .DrawBadgeRow
+;	ret
+
+.DrawBadgeRow ; e8c9 (3:68c9)
+; Draw 4 badges.
+
+	ld c, 4
+.DrawBadge
+	push de
+	push hl
+
+; Badge no.
+	ld a, [wBadgeNumberTile]
+	ld [hli], a
+	inc a
+	ld [wBadgeNumberTile], a
+
+; Names aren't printed if the badge is owned.
+	ld a, [de]
+	and a
+	ld a, [wBadgeNameTile]
+	jr nz, .SkipName
+	call .PlaceTiles
+	jr .PlaceBadge
+
+.SkipName
+	inc a
+	inc a
+	inc hl
+
+.PlaceBadge
+	ld [wBadgeNameTile], a
+	ld de, SCREEN_WIDTH - 1
+	add hl, de
+	ld a, [wBadgeOrFaceTiles]
+	call .PlaceTiles
+	add hl, de
+	call .PlaceTiles
+
+; Shift badge array back one byte.
+	push bc
+	ld hl, wBadgeOrFaceTiles + 1
+	ld de, wBadgeOrFaceTiles
+	ld bc, 8
+	call CopyData
+	pop bc
+
+	pop hl
+	ld de, 4
+	add hl, de
+
+	pop de
+	inc de
+	dec c
+	jr nz, .DrawBadge
+	ret
+
+.PlaceTiles
+	ld [hli], a
+	inc a
+	ld [hl], a
+	inc a
+	ret
+
+.FaceBadgeTiles
+	db $20, $28, $30, $38, $40, $48, $50, $58
+	
+GymLeaderFaceAndBadgeTileGraphics: ; e91b (3:691b)
+	INCBIN "gfx/badges.2bpp"
\ No newline at end of file
diff --git a/engine/flag_action_predef.asm b/engine/flag_action_predef.asm
new file mode 100644
index 00000000..df38bb87
--- /dev/null
+++ b/engine/flag_action_predef.asm
@@ -0,0 +1,73 @@
+FlagActionPredef: ; f4ec (3:74ec)
+	call GetPredefRegisters
+
+FlagAction: ; f4ef (3:74ef)
+; Perform action b on bit c
+; in the bitfield at hl.
+;  0: reset
+;  1: set
+;  2: read
+; Return the result in c.
+
+	push hl
+	push de
+	push bc
+
+	; bit
+	ld a, c
+	ld d, a
+	and 7
+	ld e, a
+
+	; byte
+	ld a, d
+	srl a
+	srl a
+	srl a
+	add l
+	ld l, a
+	jr nc, .ok
+	inc h
+.ok
+
+	; d = 1 << e (bitmask)
+	inc e
+	ld d, 1
+.shift
+	dec e
+	jr z, .shifted
+	sla d
+	jr .shift
+.shifted
+
+	ld a, b
+	and a
+	jr z, .reset
+	cp 2
+	jr z, .read
+
+.set
+	ld b, [hl]
+	ld a, d
+	or b
+	ld [hl], a
+	jr .done
+
+.reset
+	ld b, [hl]
+	ld a, d
+	xor $ff
+	and b
+	ld [hl], a
+	jr .done
+
+.read
+	ld b, [hl]
+	ld a, d
+	and b
+.done
+	pop bc
+	pop de
+	pop hl
+	ld c, a
+	ret
\ No newline at end of file
diff --git a/engine/get_bag_item_quantity.asm b/engine/get_bag_item_quantity.asm
new file mode 100644
index 00000000..2a462b5d
--- /dev/null
+++ b/engine/get_bag_item_quantity.asm
@@ -0,0 +1,18 @@
+GetQuantityOfItemInBag: ; f735 (3:7735)
+; In: b = item ID
+; Out: b = how many of that item are in the bag
+	call GetPredefRegisters
+	ld hl, wNumBagItems
+.loop
+	inc hl
+	ld a, [hli]
+	cp $ff
+	jr z, .notInBag
+	cp b
+	jr nz, .loop
+	ld a, [hl]
+	ld b, a
+	ret
+.notInBag
+	ld b, 0
+	ret
\ No newline at end of file
diff --git a/engine/heal_party.asm b/engine/heal_party.asm
new file mode 100644
index 00000000..4ef200a9
--- /dev/null
+++ b/engine/heal_party.asm
@@ -0,0 +1,99 @@
+HealParty: ; f52b (3:752b)
+; Restore HP and PP.
+
+	ld hl, wPartySpecies
+	ld de, wPartyMon1HP
+.healmon
+	ld a, [hli]
+	cp $ff
+	jr z, .done
+
+	push hl
+	push de
+
+	ld hl, wPartyMon1Status - wPartyMon1HP
+	add hl, de
+	xor a
+	ld [hl], a
+
+	push de
+	ld b, NUM_MOVES ; A Pokémon has 4 moves
+.pp
+	ld hl, wPartyMon1Moves - wPartyMon1HP
+	add hl, de
+
+	ld a, [hl]
+	and a
+	jr z, .nextmove
+
+	dec a
+	ld hl, wPartyMon1PP - wPartyMon1HP
+	add hl, de
+
+	push hl
+	push de
+	push bc
+
+	ld hl, Moves
+	ld bc, MoveEnd - Moves
+	call AddNTimes
+	ld de, wcd6d
+	ld a, BANK(Moves)
+	call FarCopyData
+	ld a, [wcd6d + 5] ; PP is byte 5 of move data
+
+	pop bc
+	pop de
+	pop hl
+
+	inc de
+	push bc
+	ld b, a
+	ld a, [hl]
+	and $c0
+	add b
+	ld [hl], a
+	pop bc
+
+.nextmove
+	dec b
+	jr nz, .pp
+	pop de
+
+	ld hl, wPartyMon1MaxHP - wPartyMon1HP
+	add hl, de
+	ld a, [hli]
+	ld [de], a
+	inc de
+	ld a, [hl]
+	ld [de], a
+
+	pop de
+	pop hl
+
+	push hl
+	ld bc, wPartyMon2 - wPartyMon1
+	ld h, d
+	ld l, e
+	add hl, bc
+	ld d, h
+	ld e, l
+	pop hl
+	jr .healmon
+
+.done
+	xor a
+	ld [wWhichPokemon], a
+	ld [wd11e], a
+
+	ld a, [wPartyCount]
+	ld b, a
+.ppup
+	push bc
+	call RestoreBonusPP
+	pop bc
+	ld hl, wWhichPokemon
+	inc [hl]
+	dec b
+	jr nz, .ppup
+	ret
\ No newline at end of file
diff --git a/engine/init_player_data.asm b/engine/init_player_data.asm
new file mode 100644
index 00000000..c1b93505
--- /dev/null
+++ b/engine/init_player_data.asm
@@ -0,0 +1,60 @@
+InitPlayerData: ; f6d6 (3:76d6)
+InitPlayerData2:
+
+	call Random
+	ld a, [hRandomSub]
+	ld [wPlayerID], a
+
+	call Random
+	ld a, [hRandomAdd]
+	ld [wPlayerID + 1], a
+
+	ld a, $ff
+	ld [wUnusedD71B], a
+	
+	ld a, 90 ; initialize happiness to 90
+	ld [wPikachuHappiness], a
+	ld a, $80
+	ld [wPikachuMood], a ; initialize mood
+	
+	ld hl, wPartyCount
+	call InitializeEmptyList
+	ld hl, wNumInBox
+	call InitializeEmptyList
+	ld hl, wNumBagItems
+	call InitializeEmptyList
+	ld hl, wNumBoxItems
+	call InitializeEmptyList
+
+START_MONEY EQU $3000
+	ld hl, wPlayerMoney + 1
+	ld a, START_MONEY / $100
+	ld [hld], a
+	xor a
+	ld [hli], a
+	inc hl
+	ld [hl], a
+
+	ld [wMonDataLocation], a
+
+	ld hl, wObtainedBadges
+	ld [hli], a
+
+	ld [hl], a
+
+	ld hl, wPlayerCoins
+	ld [hli], a
+	ld [hl], a
+
+	ld hl, wGameProgressFlags
+	ld bc, wGameProgressFlagsEnd - wGameProgressFlags
+	call FillMemory ; clear all game progress flags
+
+	jp InitializeMissableObjectsFlags
+
+InitializeEmptyList: ; f730 (3:7730)
+	xor a ; count
+	ld [hli], a
+	dec a ; terminator
+	ld [hl], a
+	ret
\ No newline at end of file
diff --git a/engine/move_mon.asm b/engine/move_mon.asm
new file mode 100644
index 00000000..a14ed9ca
--- /dev/null
+++ b/engine/move_mon.asm
@@ -0,0 +1,172 @@
+_MoveMon: ; f3a4 (3:73a4)
+	ld a, [wMoveMonType]
+	and a
+	jr z, .checkPartyMonSlots
+	cp DAYCARE_TO_PARTY
+	jr z, .checkPartyMonSlots
+	cp PARTY_TO_DAYCARE
+	ld hl, wDayCareMon
+	jr z, .asm_f3fb
+	ld hl, wNumInBox
+	ld a, [hl]
+	cp MONS_PER_BOX
+	jr nz, .partyOrBoxNotFull
+	jr .boxFull
+.checkPartyMonSlots
+	ld hl, wPartyCount
+	ld a, [hl]
+	cp PARTY_LENGTH
+	jr nz, .partyOrBoxNotFull
+.boxFull
+	scf
+	ret
+.partyOrBoxNotFull
+	inc a
+	ld [hl], a           ; increment number of mons in party/box
+	ld c, a
+	ld b, 0
+	add hl, bc
+	ld a, [wMoveMonType]
+	cp DAYCARE_TO_PARTY
+	ld a, [wDayCareMon]
+	jr z, .asm_f3dc
+	ld a, [wcf91]
+.asm_f3dc
+	ld [hli], a          ; write new mon ID
+	ld [hl], $ff         ; write new sentinel
+	ld a, [wMoveMonType]
+	dec a
+	ld hl, wPartyMons
+	ld bc, wPartyMon2 - wPartyMon1 ; $2c
+	ld a, [wPartyCount]
+	jr nz, .skipToNewMonEntry
+	ld hl, wBoxMons
+	ld bc, wBoxMon2 - wBoxMon1 ; $21
+	ld a, [wNumInBox]
+.skipToNewMonEntry
+	dec a
+	call AddNTimes
+.asm_f3fb
+	push hl
+	ld e, l
+	ld d, h
+	ld a, [wMoveMonType]
+	and a
+	ld hl, wBoxMons
+	ld bc, wBoxMon2 - wBoxMon1 ; $21
+	jr z, .asm_f417
+	cp DAYCARE_TO_PARTY
+	ld hl, wDayCareMon
+	jr z, .asm_f41d
+	ld hl, wPartyMons
+	ld bc, wPartyMon2 - wPartyMon1 ; $2c
+.asm_f417
+	ld a, [wWhichPokemon]
+	call AddNTimes
+.asm_f41d
+	push hl
+	push de
+	ld bc, wBoxMon2 - wBoxMon1
+	call CopyData
+	pop de
+	pop hl
+	ld a, [wMoveMonType]
+	and a
+	jr z, .asm_f43a
+	cp DAYCARE_TO_PARTY
+	jr z, .asm_f43a
+	ld bc, wBoxMon2 - wBoxMon1
+	add hl, bc
+	ld a, [hl]
+	inc de
+	inc de
+	inc de
+	ld [de], a
+.asm_f43a
+	ld a, [wMoveMonType]
+	cp PARTY_TO_DAYCARE
+	ld de, wDayCareMonOT
+	jr z, .asm_f459
+	dec a
+	ld hl, wPartyMonOT
+	ld a, [wPartyCount]
+	jr nz, .asm_f453
+	ld hl, wBoxMonOT
+	ld a, [wNumInBox]
+.asm_f453
+	dec a
+	call SkipFixedLengthTextEntries
+	ld d, h
+	ld e, l
+.asm_f459
+	ld hl, wBoxMonOT
+	ld a, [wMoveMonType]
+	and a
+	jr z, .asm_f46c
+	ld hl, wDayCareMonOT
+	cp DAYCARE_TO_PARTY
+	jr z, .asm_f472
+	ld hl, wPartyMonOT
+.asm_f46c
+	ld a, [wWhichPokemon]
+	call SkipFixedLengthTextEntries
+.asm_f472
+	ld bc, NAME_LENGTH
+	call CopyData
+	ld a, [wMoveMonType]
+	cp PARTY_TO_DAYCARE
+	ld de, wDayCareMonName
+	jr z, .asm_f497
+	dec a
+	ld hl, wPartyMonNicks
+	ld a, [wPartyCount]
+	jr nz, .asm_f491
+	ld hl, wBoxMonNicks
+	ld a, [wNumInBox]
+.asm_f491
+	dec a
+	call SkipFixedLengthTextEntries
+	ld d, h
+	ld e, l
+.asm_f497
+	ld hl, wBoxMonNicks
+	ld a, [wMoveMonType]
+	and a
+	jr z, .asm_f4aa
+	ld hl, wDayCareMonName
+	cp DAYCARE_TO_PARTY
+	jr z, .asm_f4b0
+	ld hl, wPartyMonNicks
+.asm_f4aa
+	ld a, [wWhichPokemon]
+	call SkipFixedLengthTextEntries
+.asm_f4b0
+	ld bc, NAME_LENGTH
+	call CopyData
+	pop hl
+	ld a, [wMoveMonType]
+	cp PARTY_TO_BOX
+	jr z, .asm_f4ea
+	cp PARTY_TO_DAYCARE
+	jr z, .asm_f4ea
+	push hl
+	srl a
+	add $2
+	ld [wMonDataLocation], a
+	call LoadMonData
+	callba CalcLevelFromExperience
+	ld a, d
+	ld [wCurEnemyLVL], a
+	pop hl
+	ld bc, wBoxMon2 - wBoxMon1
+	add hl, bc
+	ld [hli], a
+	ld d, h
+	ld e, l
+	ld bc, -18
+	add hl, bc
+	ld b, $1
+	call CalcStats
+.asm_f4ea
+	and a
+	ret
\ No newline at end of file
diff --git a/engine/overworld/boulders.asm b/engine/overworld/boulders.asm
new file mode 100644
index 00000000..edfda2d3
--- /dev/null
+++ b/engine/overworld/boulders.asm
@@ -0,0 +1,94 @@
+CheckForCollisionWhenPushingBoulder: ; c356 (3:4356)
+	call GetTileTwoStepsInFrontOfPlayer
+	call IsTilePassable
+	jr c, .done
+	ld hl, TilePairCollisionsLand
+	call CheckForTilePairCollisions2
+	ld a, $ff
+	jr c, .done ; if there is an elevation difference between the current tile and the one two steps ahead
+	ld a, [wTileInFrontOfBoulderAndBoulderCollisionResult]
+	cp $15 ; stairs tile
+	ld a, $ff
+	jr z, .done ; if the tile two steps ahead is stairs
+	call CheckForBoulderCollisionWithSprites
+.done
+	ld [wTileInFrontOfBoulderAndBoulderCollisionResult], a
+	ret
+
+; sets a to $ff if there is a collision and $00 if there is no collision
+CheckForBoulderCollisionWithSprites: ; c378 (3:4378)
+	ld a, [wBoulderSpriteIndex]
+	dec a
+	swap a
+	ld d, 0
+	ld e, a
+	ld hl, wSpriteStateData2 + $14
+	add hl, de
+	ld a, [hli] ; map Y position
+	ld [$ffdc], a
+	ld a, [hl] ; map X position
+	ld [$ffdd], a
+	ld a, [wNumSprites]
+	ld c, a
+	ld de, $f
+	ld hl, wSpriteStateData2 + $14
+	ld a, [$ffdb]
+	and $3 ; facing up or down?
+	jr z, .pushingHorizontallyLoop
+.pushingVerticallyLoop
+	inc hl
+	ld a, [$ffdd]
+	cp [hl]
+	jr nz, .nextSprite1 ; if X coordinates don't match
+	dec hl
+	ld a, [hli]
+	ld b, a
+	ld a, [$ffdb]
+	rrca
+	jr c, .pushingDown
+; pushing up
+	ld a, [$ffdc]
+	dec a
+	jr .compareYCoords
+.pushingDown
+	ld a, [$ffdc]
+	inc a
+.compareYCoords
+	cp b
+	jr z, .failure
+.nextSprite1
+	dec c
+	jr z, .success
+	add hl, de
+	jr .pushingVerticallyLoop
+.pushingHorizontallyLoop
+	ld a, [hli]
+	ld b, a
+	ld a, [$ffdc]
+	cp b
+	jr nz, .nextSprite2
+	ld b, [hl]
+	ld a, [$ffdb]
+	bit 2, a
+	jr nz, .pushingLeft
+; pushing right
+	ld a, [$ffdd]
+	inc a
+	jr .compareXCoords
+.pushingLeft
+	ld a, [$ffdd]
+	dec a
+.compareXCoords
+	cp b
+	jr z, .failure
+.nextSprite2
+	dec c
+	jr z, .success
+	add hl, de
+	jr .pushingHorizontallyLoop
+.failure
+	ld a, $ff
+	ret
+.success
+	xor a
+	ret
\ No newline at end of file
diff --git a/engine/overworld/check_player_state.asm b/engine/overworld/check_player_state.asm
new file mode 100644
index 00000000..157649a7
--- /dev/null
+++ b/engine/overworld/check_player_state.asm
@@ -0,0 +1,236 @@
+; only used for setting bit 2 of wd736 upon entering a new map
+IsPlayerStandingOnWarp: ; c0a6 (3:40a6)
+	ld a, [wNumberOfWarps]
+	and a
+	ret z
+	ld c, a
+	ld hl, wWarpEntries
+.loop
+	ld a, [wYCoord]
+	cp [hl]
+	jr nz, .nextWarp1
+	inc hl
+	ld a, [wXCoord]
+	cp [hl]
+	jr nz, .nextWarp2
+	inc hl
+	ld a, [hli] ; target warp
+	ld [wDestinationWarpID], a
+	ld a, [hl] ; target map
+	ld [$ff8b], a
+	ld hl, wd736
+	set 2, [hl] ; standing on warp flag
+	ret
+.nextWarp1
+	inc hl
+.nextWarp2
+	inc hl
+	inc hl
+	inc hl
+	dec c
+	jr nz, .loop
+	ret
+
+CheckForceBikeOrSurf: ; c0d2 (3:40d2)
+	ld hl, wd732
+	bit 5, [hl]
+	ret nz
+	ld hl, ForcedBikeOrSurfMaps
+	ld a, [wYCoord]
+	ld b, a
+	ld a, [wXCoord]
+	ld c, a
+	ld a, [wCurMap]
+	ld d, a
+.loop
+	ld a, [hli]
+	cp $ff
+	ret z ;if we reach FF then it's not part of the list
+	cp d ;compare to current map
+	jr nz, .incorrectMap
+	ld a, [hli]
+	cp b ;compare y-coord
+	jr nz, .incorrectY
+	ld a, [hli]
+	cp c ;compare x-coord
+	jr nz, .loop ; incorrect x-coord, check next item
+	ld a, [wCurMap]
+	cp SEAFOAM_ISLANDS_4
+	ld a, $2
+	ld [wSeafoamIslands4CurScript], a
+	jr z, .forceSurfing
+	ld a, [wCurMap]
+	cp SEAFOAM_ISLANDS_5
+	ld a, $2
+	ld [wSeafoamIslands5CurScript], a
+	jr z, .forceSurfing
+	;force bike riding
+	ld hl, wd732
+	set 5, [hl]
+	ld a, $1
+	ld [wWalkBikeSurfState], a
+	ld [wWalkBikeSurfStateCopy], a
+	call ForceBikeOrSurf
+	ret
+.incorrectMap
+	inc hl
+.incorrectY
+	inc hl
+	jr .loop
+.forceSurfing
+	ld a, $2
+	ld [wWalkBikeSurfState], a
+	ld [wWalkBikeSurfStateCopy], a
+	call ForceBikeOrSurf
+	ret
+	
+INCLUDE "data/force_bike_surf.asm"
+
+IsPlayerFacingEdgeOfMap: ; c148 (3:4148)
+	push hl
+	push de
+	push bc
+	ld a, [wSpriteStateData1 + 9] ; player sprite's facing direction
+	srl a
+	ld c, a
+	ld b, $0
+	ld hl, .functionPointerTable
+	add hl, bc
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	ld a, [wYCoord]
+	ld b, a
+	ld a, [wXCoord]
+	ld c, a
+	ld de, .returnaddress
+	push de
+	jp [hl]
+.returnaddress
+	pop bc
+	pop de
+	pop hl
+	ret
+
+.functionPointerTable
+	dw .facingDown
+	dw .facingUp
+	dw .facingLeft
+	dw .facingRight
+
+.facingDown
+	ld a, [wCurMapHeight]
+	add a
+	dec a
+	cp b
+	jr z, .setCarry
+	jr .resetCarry
+
+.facingUp
+	ld a, b
+	and a
+	jr z, .setCarry
+	jr .resetCarry
+
+.facingLeft
+	ld a, c
+	and a
+	jr z, .setCarry
+	jr .resetCarry
+
+.facingRight
+	ld a, [wCurMapWidth]
+	add a
+	dec a
+	cp c
+	jr z, .setCarry
+	jr .resetCarry
+.resetCarry
+	and a
+	ret
+.setCarry
+	scf
+	ret
+
+IsWarpTileInFrontOfPlayer: ; c197 (3:4197)
+	push hl
+	push de
+	push bc
+	call _GetTileAndCoordsInFrontOfPlayer
+	ld a, [wCurMap]
+	cp SS_ANNE_5
+	jr z, .ssAnne5
+	ld a, [wSpriteStateData1 + 9] ; player sprite's facing direction
+	srl a
+	ld c, a
+	ld b, 0
+	ld hl, .warpTileListPointers
+	add hl, bc
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	ld a, [wTileInFrontOfPlayer]
+	ld de, $1
+	call IsInArray
+.done
+	pop bc
+	pop de
+	pop hl
+	ret
+
+.warpTileListPointers: ; c1c0 (3:41c0)
+	dw .facingDownWarpTiles
+	dw .facingUpWarpTiles
+	dw .facingLeftWarpTiles
+	dw .facingRightWarpTiles
+
+.facingDownWarpTiles
+	db $01,$12,$17,$3D,$04,$18,$33,$FF
+
+.facingUpWarpTiles
+	db $01,$5C,$FF
+
+.facingLeftWarpTiles
+	db $1A,$4B,$FF
+
+.facingRightWarpTiles
+	db $0F,$4E,$FF
+
+.ssAnne5
+	ld a, [wTileInFrontOfPlayer]
+	cp $15
+	jr nz, .notSSAnne5Warp
+	scf
+	jr .done
+.notSSAnne5Warp
+	and a
+	jr .done
+
+IsPlayerStandingOnDoorTileOrWarpTile: ; c1e6 (3:41e6)
+	push hl
+	push de
+	push bc
+	callba IsPlayerStandingOnDoorTile ; 6:6785
+	jr c, .done
+	ld a, [wCurMapTileset]
+	add a
+	ld c, a
+	ld b, $0
+	ld hl, WarpTileIDPointers
+	add hl, bc
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	ld de, $1
+	aCoord 8, 9
+	call IsInArray
+	jr nc, .done
+	ld hl, wd736
+	res 2, [hl]
+.done
+	pop bc
+	pop de
+	pop hl
+	ret
+
+INCLUDE "data/warp_tile_ids.asm"
\ No newline at end of file
diff --git a/engine/overworld/clear_loadmapdata_vars.asm b/engine/overworld/clear_loadmapdata_vars.asm
new file mode 100644
index 00000000..2e7cd165
--- /dev/null
+++ b/engine/overworld/clear_loadmapdata_vars.asm
@@ -0,0 +1,20 @@
+ClearVariablesAfterLoadingMapData: ; c07c (3:407c)
+	ld a, $90
+	ld [hWY], a
+	ld [rWY], a
+	xor a
+	ld [H_AUTOBGTRANSFERENABLED], a
+	ld [wStepCounter], a
+	ld [wLoneAttackNo], a ; wGymLeaderNo
+	ld [hJoyPressed], a
+	ld [hJoyReleased], a
+	ld [hJoyHeld], a
+	ld [wActionResultOrTookBattleTurn], a
+	ld [wUnusedD5A3], a
+	ld hl, wCardKeyDoorY
+	ld [hli], a
+	ld [hl], a
+	ld hl, wWhichTrade
+	ld bc, $1e
+	call FillMemory
+	ret
\ No newline at end of file
diff --git a/engine/overworld/daycare_exp.asm b/engine/overworld/daycare_exp.asm
new file mode 100644
index 00000000..a7c7bd91
--- /dev/null
+++ b/engine/overworld/daycare_exp.asm
@@ -0,0 +1,18 @@
+IncrementDayCareMonExp: ; c684 (3:4684)
+	ld a, [wDayCareInUse]
+	and a
+	ret z
+	ld hl, wDayCareMonExp + 2
+	inc [hl]
+	ret nz
+	dec hl
+	inc [hl]
+	ret nz
+	dec hl
+	inc [hl]
+	ld a, [hl]
+	cp $50
+	ret c
+	ld a, $50
+	ld [hl], a
+	ret
\ No newline at end of file
diff --git a/engine/overworld/get_coords_tile_in_front_of_player.asm b/engine/overworld/get_coords_tile_in_front_of_player.asm
new file mode 100644
index 00000000..a0d38d7c
--- /dev/null
+++ b/engine/overworld/get_coords_tile_in_front_of_player.asm
@@ -0,0 +1,87 @@
+GetTileAndCoordsInFrontOfPlayer: ; c2d4 (3:42d1)
+	call GetPredefRegisters
+	
+_GetTileAndCoordsInFrontOfPlayer: ; c2d4 (3:42d4)
+	ld a, [wYCoord]
+	ld d, a
+	ld a, [wXCoord]
+	ld e, a
+	ld a, [wSpriteStateData1 + 9] ; player's sprite facing direction
+	and a ; cp SPRITE_FACING_DOWN
+	jr nz, .notFacingDown
+; facing down
+	aCoord 8, 11
+	inc d
+	jr .storeTile
+.notFacingDown
+	cp SPRITE_FACING_UP
+	jr nz, .notFacingUp
+; facing up
+	aCoord 8, 7
+	dec d
+	jr .storeTile
+.notFacingUp
+	cp SPRITE_FACING_LEFT
+	jr nz, .notFacingLeft
+; facing left
+	aCoord 6, 9
+	dec e
+	jr .storeTile
+.notFacingLeft
+	cp SPRITE_FACING_RIGHT
+	jr nz, .storeTile
+; facing right
+	aCoord 10, 9
+	inc e
+.storeTile
+	ld c, a
+	ld [wTileInFrontOfPlayer], a
+	ret
+	
+GetTileTwoStepsInFrontOfPlayer: ; c309 (3:4309)
+	xor a
+	ld [$ffdb], a
+	ld hl, wYCoord
+	ld a, [hli]
+	ld d, a
+	ld e, [hl]
+	ld a, [wSpriteStateData1 + 9] ; player's sprite facing direction
+	and a ; cp SPRITE_FACING_DOWN
+	jr nz, .notFacingDown
+; facing down
+	ld hl, $ffdb
+	set 0, [hl]
+	aCoord 8, 13
+	inc d
+	jr .storeTile
+.notFacingDown
+	cp SPRITE_FACING_UP
+	jr nz, .notFacingUp
+; facing up
+	ld hl, $ffdb
+	set 1, [hl]
+	aCoord 8, 5
+	dec d
+	jr .storeTile
+.notFacingUp
+	cp SPRITE_FACING_LEFT
+	jr nz, .notFacingLeft
+; facing left
+	ld hl, $ffdb
+	set 2, [hl]
+	aCoord 4, 9
+	dec e
+	jr .storeTile
+.notFacingLeft
+	cp SPRITE_FACING_RIGHT
+	jr nz, .storeTile
+; facing right
+	ld hl, $ffdb
+	set 3, [hl]
+	aCoord 12, 9
+	inc e
+.storeTile
+	ld c, a
+	ld [wTileInFrontOfBoulderAndBoulderCollisionResult], a
+	ld [wTileInFrontOfPlayer], a
+	ret
\ No newline at end of file
diff --git a/engine/overworld/load_tileset_header.asm b/engine/overworld/load_tileset_header.asm
new file mode 100644
index 00000000..aeab3e24
--- /dev/null
+++ b/engine/overworld/load_tileset_header.asm
@@ -0,0 +1,51 @@
+LoadTilesetHeader: ; c4f4 (3:44f4)
+	call GetPredefRegisters
+	push hl
+	ld d, 0
+	ld a, [wCurMapTileset]
+	add a
+	add a
+	ld e, a
+	ld hl, Tilesets
+	add hl, de
+	add hl, de
+	add hl, de
+	ld de, wTilesetBank
+	ld bc, $b
+	call CopyData
+	ld a, [hl]
+	ld [hTilesetType], a
+	xor a
+	ld [$ffd8], a
+	pop hl
+	ld a, [wCurMapTileset]
+	push hl
+	push de
+	ld hl, DungeonTilesets
+	ld de, $1
+	call IsInArray
+	pop de
+	pop hl
+	jr c, .notDungeonTileset
+	ld a, [wCurMapTileset]
+	ld b, a
+	ld a, [hPreviousTileset]
+	cp b
+	jr z, .done
+.notDungeonTileset
+	ld a, [wDestinationWarpID]
+	cp $ff
+	jr z, .done
+	call LoadDestinationWarpPosition
+	ld a, [wYCoord]
+	and $1
+	ld [wYBlockCoord], a
+	ld a, [wXCoord]
+	and $1
+	ld [wXBlockCoord], a
+.done
+	ret
+
+INCLUDE "data/dungeon_tilesets.asm"
+
+INCLUDE "data/tileset_headers.asm"
\ No newline at end of file
diff --git a/engine/overworld/load_wild_data.asm b/engine/overworld/load_wild_data.asm
new file mode 100644
index 00000000..083e08bf
--- /dev/null
+++ b/engine/overworld/load_wild_data.asm
@@ -0,0 +1,33 @@
+LoadWildData: ; cb62 (3:4b62)
+	ld hl,WildDataPointers
+	ld a,[wCurMap]
+
+	; get wild data for current map
+	ld c,a
+	ld b,0
+	add hl,bc
+	add hl,bc
+	ld a,[hli]
+	ld h,[hl]
+	ld l,a       ; hl now points to wild data for current map
+	ld a,[hli]
+	ld [wGrassRate],a
+	and a
+	jr z,.NoGrassData ; if no grass data, skip to surfing data
+	push hl
+	ld de,wGrassMons ; otherwise, load grass data
+	ld bc,$0014
+	call CopyData
+	pop hl
+	ld bc,$0014
+	add hl,bc
+.NoGrassData
+	ld a,[hli]
+	ld [wWaterRate],a
+	and a
+	ret z        ; if no water data, we're done
+	ld de,wWaterMons  ; otherwise, load surfing data
+	ld bc,$0014
+	jp CopyData
+	
+INCLUDE "data/wild_mons.asm"
\ No newline at end of file
diff --git a/engine/overworld/missable_objects.asm b/engine/overworld/missable_objects.asm
new file mode 100644
index 00000000..f18a0823
--- /dev/null
+++ b/engine/overworld/missable_objects.asm
@@ -0,0 +1,212 @@
+MarkTownVisitedAndLoadMissableObjects: ; ef93 (3:6f93)
+	ld a, [wCurMap]
+	cp ROUTE_1
+	jr nc, .notInTown
+	ld c, a
+	ld b, FLAG_SET
+	ld hl, wTownVisitedFlag   ; mark town as visited (for flying)
+	predef FlagActionPredef
+.notInTown
+	ld hl, MapHSPointers
+	ld a, [wCurMap]
+	ld b, $0
+	ld c, a
+	add hl, bc
+	add hl, bc
+	ld a, [hli]                ; load missable objects pointer in hl
+	ld h, [hl]
+	; fall through
+
+; LoadMissableObjects: ; efb2 (3:6fb2)
+; seems to not exist in yellow (predef replaced with something near TryPushingBoulder)
+	ld l, a
+	push hl
+	ld a, l
+	sub MapHS00 & $ff ; calculate difference between out pointer and the base pointer
+	ld l, a
+	ld a, h
+	sbc MapHS00 / $100
+	ld h, a
+	ld a, h
+	ld [H_DIVIDEND], a
+	ld a, l
+	ld [H_DIVIDEND+1], a
+	xor a
+	ld [H_DIVIDEND+2], a
+	ld [H_DIVIDEND+3], a
+	ld a, $3
+	ld [H_DIVISOR], a
+	ld b, $2
+	call Divide                ; divide difference by 3, resulting in the global offset (number of missable items before ours)
+	ld a, [wCurMap]
+	ld b, a
+	ld a, [H_DIVIDEND+3]
+	ld c, a                    ; store global offset in c
+	ld de, wMissableObjectList
+	pop hl
+.writeMissableObjectsListLoop
+	ld a, [hli]
+	cp $ff
+	jr z, .done     ; end of list
+	cp b
+	jr nz, .done    ; not for current map anymore
+	ld a, [hli]
+	inc hl
+	ld [de], a                 ; write (map-local) sprite ID
+	inc de
+	ld a, c
+	inc c
+	ld [de], a                 ; write (global) missable object index
+	inc de
+	jr .writeMissableObjectsListLoop
+.done
+	ld a, $ff
+	ld [de], a                 ; write sentinel
+	ret
+
+InitializeMissableObjectsFlags: ; eff1 (3:6ff1)
+	ld hl, wMissableObjectFlags
+	ld bc, wMissableObjectFlagsEnd - wMissableObjectFlags
+	xor a
+	call FillMemory ; clear missable objects flags
+	ld hl, MapHS00
+	xor a
+	ld [wMissableObjectCounter], a
+.missableObjectsLoop
+	ld a, [hli]
+	cp $ff          ; end of list
+	ret z
+	push hl
+	inc hl
+	ld a, [hl]
+	cp Hide
+	jr nz, .skip
+	ld hl, wMissableObjectFlags
+	ld a, [wMissableObjectCounter]
+	ld c, a
+	ld b, FLAG_SET
+	call MissableObjectFlagAction ; set flag if Item is hidden
+.skip
+	ld hl, wMissableObjectCounter
+	inc [hl]
+	pop hl
+	inc hl
+	inc hl
+	jr .missableObjectsLoop
+
+; tests if current sprite is a missable object that is hidden/has been removed
+IsObjectHidden: ; f022 (3:7022)
+	ld a, [H_CURRENTSPRITEOFFSET]
+	swap a
+	ld b, a
+	ld hl, wMissableObjectList
+.loop
+	ld a, [hli]
+	cp $ff
+	jr z, .notHidden ; not missable -> not hidden
+	cp b
+	ld a, [hli]
+	jr nz, .loop
+	ld c, a
+	ld b, FLAG_TEST
+	ld hl, wMissableObjectFlags
+	call MissableObjectFlagAction
+	ld a, c
+	and a
+	jr nz, .hidden
+.notHidden
+	xor a
+.hidden
+	ld [$ffe5], a
+	ret
+
+; adds missable object (items, leg. pokemon, etc.) to the map
+; [wMissableObjectIndex]: index of the missable object to be added (global index)
+ShowObject: ; f044 (3:7044)
+ShowObject2:
+	ld hl, wMissableObjectFlags
+	ld a, [wMissableObjectIndex]
+	ld c, a
+	ld b, FLAG_RESET
+	call MissableObjectFlagAction   ; reset "removed" flag
+	jp UpdateSprites
+
+; removes missable object (items, leg. pokemon, etc.) from the map
+; [wMissableObjectIndex]: index of the missable object to be removed (global index)
+HideObject: ; f053 (3:7053)
+	ld hl, wMissableObjectFlags
+	ld a, [wMissableObjectIndex]
+	ld c, a
+	ld b, FLAG_SET
+	call MissableObjectFlagAction   ; set "removed" flag
+	jp UpdateSprites
+
+MissableObjectFlagAction: ; f062 (3:7062)
+; identical to FlagAction
+
+	push hl
+	push de
+	push bc
+
+	; bit
+	ld a, c
+	ld d, a
+	and 7
+	ld e, a
+
+	; byte
+	ld a, d
+	srl a
+	srl a
+	srl a
+	add l
+	ld l, a
+	jr nc, .ok
+	inc h
+.ok
+
+	; d = 1 << e (bitmask)
+	inc e
+	ld d, 1
+.shift
+	dec e
+	jr z, .shifted
+	sla d
+	jr .shift
+.shifted
+
+	ld a, b
+	and a
+	jr z, .reset
+	cp 2
+	jr z, .read
+
+.set
+	ld a, [hl]
+	ld b, a
+	ld a, d
+	or b
+	ld [hl], a
+	jr .done
+
+.reset
+	ld a, [hl]
+	ld b, a
+	ld a, d
+	xor $ff
+	and b
+	ld [hl], a
+	jr .done
+
+.read
+	ld a, [hl]
+	ld b, a
+	ld a, d
+	and b
+
+.done
+	pop bc
+	pop de
+	pop hl
+	ld c, a
+	ret
\ No newline at end of file
diff --git a/engine/overworld/npc_pathfinding.asm b/engine/overworld/npc_pathfinding.asm
new file mode 100644
index 00000000..ed7db530
--- /dev/null
+++ b/engine/overworld/npc_pathfinding.asm
@@ -0,0 +1,201 @@
+FindPathToPlayer: ; f74a (3:774a)
+	xor a
+	ld hl, hFindPathNumSteps
+	ld [hli], a ; hFindPathNumSteps
+	ld [hli], a ; hFindPathFlags
+	ld [hli], a ; hFindPathYProgress
+	ld [hl], a  ; hFindPathXProgress
+	ld hl, wNPCMovementDirections2
+	ld de, $0
+.loop
+	ld a, [hFindPathYProgress]
+	ld b, a
+	ld a, [hNPCPlayerYDistance] ; Y distance in steps
+	call CalcDifference
+	ld d, a
+	and a
+	jr nz, .asm_f76a
+	ld a, [hFindPathFlags]
+	set 0, a ; current end of path matches the player's Y coordinate
+	ld [hFindPathFlags], a
+.asm_f76a
+	ld a, [hFindPathXProgress]
+	ld b, a
+	ld a, [hNPCPlayerXDistance] ; X distance in steps
+	call CalcDifference
+	ld e, a
+	and a
+	jr nz, .asm_f77c
+	ld a, [hFindPathFlags]
+	set 1, a ; current end of path matches the player's X coordinate
+	ld [hFindPathFlags], a
+.asm_f77c
+	ld a, [hFindPathFlags]
+	cp $3 ; has the end of the path reached the player's position?
+	jr z, .done
+; Compare whether the X distance between the player and the current of the path
+; is greater or if the Y distance is. Then, try to reduce whichever is greater.
+	ld a, e
+	cp d
+	jr c, .yDistanceGreater
+; x distance is greater
+	ld a, [hNPCPlayerRelativePosFlags]
+	bit 1, a
+	jr nz, .playerIsLeftOfNPC
+	ld d, NPC_MOVEMENT_RIGHT
+	jr .next1
+.playerIsLeftOfNPC
+	ld d, NPC_MOVEMENT_LEFT
+.next1
+	ld a, [hFindPathXProgress]
+	add 1
+	ld [hFindPathXProgress], a
+	jr .storeDirection
+.yDistanceGreater
+	ld a, [hNPCPlayerRelativePosFlags]
+	bit 0, a
+	jr nz, .playerIsAboveNPC
+	ld d, NPC_MOVEMENT_DOWN
+	jr .next2
+.playerIsAboveNPC
+	ld d, NPC_MOVEMENT_UP
+.next2
+	ld a, [hFindPathYProgress]
+	add 1
+	ld [hFindPathYProgress], a
+.storeDirection
+	ld a, d
+	ld [hli], a
+	ld a, [hFindPathNumSteps]
+	inc a
+	ld [hFindPathNumSteps], a
+	jp .loop
+.done
+	ld [hl], $ff
+	ret
+
+CalcPositionOfPlayerRelativeToNPC: ; f7b9 (3:77b9)
+	xor a
+	ld [hNPCPlayerRelativePosFlags], a
+	ld a, [wSpriteStateData1 + 4] ; player's sprite screen Y position in pixels
+	ld d, a
+	ld a, [wSpriteStateData1 + 6] ; player's sprite screen X position in pixels
+	ld e, a
+	ld hl, wSpriteStateData1
+	ld a, [hNPCSpriteOffset]
+	add l
+	add $4
+	ld l, a
+	jr nc, .noCarry
+	inc h
+.noCarry
+	ld a, d
+	ld b, a
+	ld a, [hli] ; NPC sprite screen Y position in pixels
+	call CalcDifference
+	jr nc, .NPCSouthOfOrAlignedWithPlayer
+.NPCNorthOfPlayer
+	push hl
+	ld hl, hNPCPlayerRelativePosFlags
+	bit 0, [hl]
+	set 0, [hl]
+	pop hl
+	jr .divideYDistance
+.NPCSouthOfOrAlignedWithPlayer
+	push hl
+	ld hl, hNPCPlayerRelativePosFlags
+	bit 0, [hl]
+	res 0, [hl]
+	pop hl
+.divideYDistance
+	push hl
+	ld hl, hDividend2
+	ld [hli], a
+	ld a, 16
+	ld [hli], a
+	call DivideBytes ; divide Y absolute distance by 16
+	ld a, [hl] ; quotient
+	ld [hNPCPlayerYDistance], a
+	pop hl
+	inc hl
+	ld b, e
+	ld a, [hl] ; NPC sprite screen X position in pixels
+	call CalcDifference
+	jr nc, .NPCEastOfOrAlignedWithPlayer
+.NPCWestOfPlayer
+	push hl
+	ld hl, hNPCPlayerRelativePosFlags
+	bit 1, [hl]
+	set 1, [hl]
+	pop hl
+	jr .divideXDistance
+.NPCEastOfOrAlignedWithPlayer
+	push hl
+	ld hl, hNPCPlayerRelativePosFlags
+	bit 1, [hl]
+	res 1, [hl]
+	pop hl
+.divideXDistance
+	ld [hDividend2], a
+	ld a, 16
+	ld [hDivisor2], a
+	call DivideBytes ; divide X absolute distance by 16
+	ld a, [hQuotient2]
+	ld [hNPCPlayerXDistance], a
+	ld a, [hNPCPlayerRelativePosPerspective]
+	and a
+	ret z
+	ld a, [hNPCPlayerRelativePosFlags]
+	cpl
+	and $3
+	ld [hNPCPlayerRelativePosFlags], a
+	ret
+
+ConvertNPCMovementDirectionsToJoypadMasks: ; f830 (3:7830)
+	ld a, [hNPCMovementDirections2Index]
+	ld [wNPCMovementDirections2Index], a
+	dec a
+	ld de, wSimulatedJoypadStatesEnd
+	ld hl, wNPCMovementDirections2
+	add l
+	ld l, a
+	jr nc, .loop
+	inc h
+.loop
+	ld a, [hld]
+	call ConvertNPCMovementDirectionToJoypadMask
+	ld [de], a
+	inc de
+	ld a, [hNPCMovementDirections2Index]
+	dec a
+	ld [hNPCMovementDirections2Index], a
+	jr nz, .loop
+	ret
+
+ConvertNPCMovementDirectionToJoypadMask: ; f84f (3:784f)
+	push hl
+	ld b, a
+	ld hl, NPCMovementDirectionsToJoypadMasksTable
+.loop
+	ld a, [hli]
+	cp $ff
+	jr z, .done
+	cp b
+	jr z, .loadJoypadMask
+	inc hl
+	jr .loop
+.loadJoypadMask
+	ld a, [hl]
+.done
+	pop hl
+	ret
+
+NPCMovementDirectionsToJoypadMasksTable: ; f862 (3:7862)
+	db NPC_MOVEMENT_UP, D_UP
+	db NPC_MOVEMENT_DOWN, D_DOWN
+	db NPC_MOVEMENT_LEFT, D_LEFT
+	db NPC_MOVEMENT_RIGHT, D_RIGHT
+	db $ff
+
+; unreferenced
+	ret
\ No newline at end of file
diff --git a/engine/overworld/print_safari_steps.asm b/engine/overworld/print_safari_steps.asm
new file mode 100644
index 00000000..3f2ada03
--- /dev/null
+++ b/engine/overworld/print_safari_steps.asm
@@ -0,0 +1,36 @@
+PrintSafariZoneSteps: ; c27b (3:427b)
+	ld a, [wCurMap]
+	cp SAFARI_ZONE_EAST
+	ret c
+	cp UNKNOWN_DUNGEON_2
+	ret nc
+	coord hl, 0, 0
+	lb bc, 3, 7
+	call TextBoxBorder
+	coord hl, 1, 1
+	ld de, wSafariSteps
+	lb bc, 2, 3
+	call PrintNumber
+	coord hl, 4, 1
+	ld de, SafariSteps
+	call PlaceString
+	coord hl, 1, 3
+	ld de, SafariBallText
+	call PlaceString
+	ld a, [wNumSafariBalls]
+	cp 10
+	jr nc, .numSafariBallsTwoDigits
+	coord hl, 5, 3
+	ld a, " "
+	ld [hl], a
+.numSafariBallsTwoDigits
+	coord hl, 6, 3
+	ld de, wNumSafariBalls
+	lb bc, 1, 2
+	jp PrintNumber
+
+SafariSteps: ; c2c4 (3:42c4)
+	db "/500@"
+
+SafariBallText: ; c5c9 (3:42c9)
+	db "BALL×× @"
\ No newline at end of file
diff --git a/engine/overworld/replace_tile_block.asm b/engine/overworld/replace_tile_block.asm
new file mode 100644
index 00000000..32c652ea
--- /dev/null
+++ b/engine/overworld/replace_tile_block.asm
@@ -0,0 +1,126 @@
+; replaces a tile block with the one specified in [wNewTileBlockID]
+; and redraws the map view if necessary
+; b = Y
+; c = X
+ReplaceTileBlock: ; ed1b (3:6d1b)
+	call GetPredefRegisters
+	ld hl, wOverworldMap
+	ld a, [wCurMapWidth]
+	add $6
+	ld e, a
+	ld d, $0
+	add hl, de
+	add hl, de
+	add hl, de
+	ld e, $3
+	add hl, de
+	ld e, a
+	ld a, b
+	and a
+	jr z, .addX
+; add width * Y
+.addWidthYTimesLoop
+	add hl, de
+	dec b
+	jr nz, .addWidthYTimesLoop
+.addX
+	add hl, bc ; add X
+	ld a, [wNewTileBlockID]
+	ld [hl], a
+	ld a, [wCurrentTileBlockMapViewPointer]
+	ld c, a
+	ld a, [wCurrentTileBlockMapViewPointer + 1]
+	ld b, a
+	call CompareHLWithBC
+	ret c ; return if the replaced tile block is below the map view in memory
+	push hl
+	ld l, e
+	ld h, $0
+	ld e, $6
+	ld d, h
+	add hl, hl
+	add hl, hl
+	add hl, de
+	add hl, bc
+	pop bc
+	call CompareHLWithBC
+	ret c ; return if the replaced tile block is above the map view in memory
+
+RedrawMapView: ; ed59 (3:6d59)
+	ld a, [wIsInBattle]
+	inc a
+	ret z
+	ld a, [H_AUTOBGTRANSFERENABLED]
+	push af
+	ld a, [hTilesetType]
+	push af
+	xor a
+	ld [H_AUTOBGTRANSFERENABLED], a
+	ld [hTilesetType], a ; no flower/water BG tile animations
+	call LoadCurrentMapView
+	call RunDefaultPaletteCommand
+	ld hl, wMapViewVRAMPointer
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	ld de, -2 * 32
+	add hl, de
+	ld a, h
+	and $3
+	or $98
+	ld a, l
+	ld [wBuffer], a
+	ld a, h
+	ld [wBuffer + 1], a ; this copy of the address is not used
+	ld a, 2
+	ld [$ffbe], a
+	ld c, 9 ; number of rows of 2x2 tiles (this covers the whole screen)
+.redrawRowLoop
+	push bc
+	push hl
+	push hl
+	ld hl, wTileMap - 2 * SCREEN_WIDTH
+	ld de, SCREEN_WIDTH
+	ld a, [$ffbe]
+.calcWRAMAddrLoop
+	add hl, de
+	dec a
+	jr nz, .calcWRAMAddrLoop
+	call CopyToRedrawRowOrColumnSrcTiles
+	pop hl
+	ld de, $20
+	ld a, [$ffbe]
+	ld c, a
+.calcVRAMAddrLoop
+	add hl, de
+	ld a, h
+	and $3
+	or $98
+	dec c
+	jr nz, .calcVRAMAddrLoop
+	ld [hRedrawRowOrColumnDest + 1], a
+	ld a, l
+	ld [hRedrawRowOrColumnDest], a
+	ld a, REDRAW_ROW
+	ld [hRedrawRowOrColumnMode], a
+	call DelayFrame
+	ld hl, $ffbe
+	inc [hl]
+	inc [hl]
+	pop hl
+	pop bc
+	dec c
+	jr nz, .redrawRowLoop
+	pop af
+	ld [hTilesetType], a
+	pop af
+	ld [H_AUTOBGTRANSFERENABLED], a
+	ret
+
+CompareHLWithBC: ; edcb (3:6dcb)
+	ld a, h
+	sub b
+	ret nz
+	ld a, l
+	sub c
+	ret
\ No newline at end of file
diff --git a/engine/overworld/step_functions.asm b/engine/overworld/step_functions.asm
new file mode 100644
index 00000000..84cf4e82
--- /dev/null
+++ b/engine/overworld/step_functions.asm
@@ -0,0 +1,151 @@
+ApplyOutOfBattlePoisonDamage: ; c3de (3:43de)
+	ld a, [wd730]
+	add a
+	jp c, .noBlackOut ; no black out if joypad states are being simulated
+	ld a, [wd493]
+	bit 7, a
+	jp nz, .noBlackOut
+	ld a, [wd72e]
+	bit 6, a
+	jp nz, .noBlackOut
+	ld a, [wPartyCount]
+	and a
+	jp z, .noBlackOut
+	call IncrementDayCareMonExp
+	call Func_c4c7
+	ld a, [wStepCounter]
+	and $3 ; is the counter a multiple of 4?
+	jp nz, .skipPoisonEffectAndSound ; only apply poison damage every fourth step
+	ld [wWhichPokemon], a
+	ld hl, wPartyMon1Status
+	ld de, wPartySpecies
+.applyDamageLoop
+	ld a, [hl]
+	and (1 << PSN)
+	jr z, .nextMon2 ; not poisoned
+	dec hl
+	dec hl
+	ld a, [hld]
+	ld b, a
+	ld a, [hli]
+	or b
+	jr z, .nextMon ; already fainted
+; subtract 1 from HP
+	ld a, [hl]
+	dec a
+	ld [hld], a
+	inc a
+	jr nz, .noBorrow
+; borrow 1 from upper byte of HP
+	dec [hl]
+	inc hl
+	jr .nextMon
+.noBorrow
+	ld a, [hli]
+	or [hl]
+	jr nz, .nextMon ; didn't faint from damage
+; the mon fainted from the damage
+	push hl
+	inc hl
+	inc hl
+	ld [hl], a
+	ld a, [de]
+	ld [wd11e], a
+	push de
+	ld a, [wWhichPokemon]
+	ld hl, wPartyMonNicks
+	call GetPartyMonName
+	xor a
+	ld [wJoyIgnore], a
+	call EnableAutoTextBoxDrawing
+	ld a, $d0
+	ld [hSpriteIndexOrTextID], a
+	call DisplayTextID
+	callab IsThisPartymonStarterPikachu_Party
+	jr nc, .curMonNotPlayerPikachu
+	ld e, $3
+	callab PlayPikachuSoundClip
+	calladb_ModifyPikachuHappiness PIKAHAPPY_PSNFNT
+.curMonNotPlayerPikachu
+	pop de
+	pop hl
+.nextMon
+	inc hl
+	inc hl
+.nextMon2
+	inc de
+	ld a, [de]
+	inc a
+	jr z, .applyDamageLoopDone
+	ld bc, wPartyMon2 - wPartyMon1
+	add hl, bc
+	push hl
+	ld hl, wWhichPokemon
+	inc [hl]
+	pop hl
+	jr .applyDamageLoop
+.applyDamageLoopDone
+	ld hl, wPartyMon1Status
+	ld a, [wPartyCount]
+	ld d, a
+	ld e, 0
+.countPoisonedLoop
+	ld a, [hl]
+	and (1 << PSN)
+	or e
+	ld e, a
+	ld bc, wPartyMon2 - wPartyMon1
+	add hl, bc
+	dec d
+	jr nz, .countPoisonedLoop
+	ld a, e
+	and a ; are any party members poisoned?
+	jr z, .skipPoisonEffectAndSound
+	ld b, $2
+	predef InvertBGPal_4Frames ; change BG white to dark grey for 4 frames
+	ld a, SFX_POISONED
+	call PlaySound
+.skipPoisonEffectAndSound
+	predef AnyPartyAlive
+	ld a, d
+	and a
+	jr nz, .noBlackOut
+	call EnableAutoTextBoxDrawing
+	ld a, $d1
+	ld [hSpriteIndexOrTextID], a
+	call DisplayTextID
+	ld hl, wd72e
+	set 5, [hl]
+	ld a, $ff
+	jr .done
+.noBlackOut
+	xor a
+.done
+	ld [wOutOfBattleBlackout], a
+	ret
+	
+Func_c4c7: ; c4c7 (3:44c7)
+	ld a, [wStepCounter]
+	and a
+	jr nz, .asm_c4de
+	call Random
+	and $1
+	jr z, .asm_c4de
+	calladb_ModifyPikachuHappiness $6
+.asm_c4de
+	ld hl, wPikachuMood
+	ld a, [hl]
+	cp $80
+	jr z, .asm_c4ef
+	jr c, .asm_c4ea
+	dec a
+	dec a
+.asm_c4ea
+	inc a
+	ld [hl], a
+	cp $80
+	ret nz
+.asm_c4ef
+	xor a
+	ld [wd49c], a
+	ret
\ No newline at end of file
diff --git a/engine/overworld/try_pushing_boulder.asm b/engine/overworld/try_pushing_boulder.asm
new file mode 100644
index 00000000..d978a083
--- /dev/null
+++ b/engine/overworld/try_pushing_boulder.asm
@@ -0,0 +1,106 @@
+TryPushingBoulder: ; f0a1 (3:70a1)
+	ld a, [wd728]
+	bit 0, a ; using Strength?
+	ret z
+; where LoadMissableObjects predef points to now
+	ld a, [wFlags_0xcd60]
+	bit 1, a ; has boulder dust animation from previous push played yet?
+	ret nz
+	xor a
+	ld [hSpriteIndexOrTextID], a
+	call IsSpriteInFrontOfPlayer
+	ld a, [hSpriteIndexOrTextID]
+	ld [wBoulderSpriteIndex], a
+	and a
+	jp z, ResetBoulderPushFlags
+	ld hl, wSpriteStateData1 + 1
+	ld d, $0
+	ld a, [hSpriteIndexOrTextID]
+	swap a
+	ld e, a
+	add hl, de
+	res 7, [hl]
+	call GetSpriteMovementByte2Pointer
+	ld a, [hl]
+	cp BOULDER_MOVEMENT_BYTE_2
+	jp nz, ResetBoulderPushFlags
+	ld hl, wFlags_0xcd60
+	bit 6, [hl]
+	set 6, [hl] ; indicate that the player has tried pushing
+	ret z ; the player must try pushing twice before the boulder will move
+	ld a, [hJoyHeld]
+	and D_RIGHT | D_LEFT | D_UP | D_DOWN
+	ret z
+	predef CheckForCollisionWhenPushingBoulder
+	ld a, [wTileInFrontOfBoulderAndBoulderCollisionResult]
+	and a ; was there a collision?
+	jp nz, ResetBoulderPushFlags
+	ld a, [hJoyHeld]
+	ld b, a
+	ld a, [wSpriteStateData1 + 9] ; player's sprite facing direction
+	cp SPRITE_FACING_UP
+	jr z, .pushBoulderUp
+	cp SPRITE_FACING_LEFT
+	jr z, .pushBoulderLeft
+	cp SPRITE_FACING_RIGHT
+	jr z, .pushBoulderRight
+.pushBoulderDown
+	bit 7, b
+	ret z
+	ld de, PushBoulderDownMovementData
+	jr .done
+.pushBoulderUp
+	bit 6, b
+	ret z
+	ld de, PushBoulderUpMovementData
+	jr .done
+.pushBoulderLeft
+	bit 5, b
+	ret z
+	ld de, PushBoulderLeftMovementData
+	jr .done
+.pushBoulderRight
+	bit 4, b
+	ret z
+	ld de, PushBoulderRightMovementData
+.done
+	call MoveSprite
+	ld a, SFX_PUSH_BOULDER
+	call PlaySound
+	ld hl, wFlags_0xcd60
+	set 1, [hl]
+	ret
+
+PushBoulderUpMovementData: ; f129 (3:7129)
+	db NPC_MOVEMENT_UP,$FF
+
+PushBoulderDownMovementData: ; f12b (3:712b)
+	db NPC_MOVEMENT_DOWN,$FF
+
+PushBoulderLeftMovementData: ; f12d (3:712d)
+	db NPC_MOVEMENT_LEFT,$FF
+
+PushBoulderRightMovementData: ; f12f (3:712f)
+	db NPC_MOVEMENT_RIGHT,$FF
+
+DoBoulderDustAnimation: ; f131 (3:7131)
+	ld a, [wd730]
+	bit 0, a
+	ret nz
+	callab AnimateBoulderDust
+	call DiscardButtonPresses
+	ld [wJoyIgnore], a
+	call ResetBoulderPushFlags
+	set 7, [hl]
+	ld a, [wBoulderSpriteIndex]
+	ld [H_SPRITEINDEX], a
+	call GetSpriteMovementByte2Pointer
+	ld [hl], $10
+	ld a, SFX_CUT
+	jp PlaySound
+
+ResetBoulderPushFlags: ; f159 (3:7159)
+	ld hl, wFlags_0xcd60
+	res 1, [hl]
+	res 6, [hl]
+	ret
\ No newline at end of file