Mystery Box functionality

It was a long shot, but I did it! I added the Mystery Box from Pokemon GO! Very happy with the results here.

So here's how it works: When used, the game will replace Pokemon encountered with Meltan until the player leaves the map. This is sort of how it works in GO, with the player unable to close it and naturally petering out as they play.

Now multiple Meltan can be obtained, and in abundance, just like GO. Technically, someone could use this as a pseudo-Repel to replace hard encounters with easy ones.

Oh, and I'm pretty sure this happens vs static encounters as well, but it's awkward to account for I think that's hilarious, so...

README.md

@@ -59,8 +59,10 @@ Naturally, these types get appropriate moves. They are currently distributed to
 New Items:
 ====
 There are some new items here, with the aim of accomodating new Pokemon, adding features, and acting as methods of getting to new locations. 
+- To accomodate Meltan, the Mystery Box from Pokemon GO is featured. When used, wild encounters are replaced with Meltan until one leaves the location.
+	- Melmetal is obtained by using a Candy Jar on Meltan, which is obtained as a special reward later!
 - The Ice, Poison and Heart Stones have been added, the latter two being from the SpaceWorld '97 demo.
-	- Additional evolution items include the Protector, Black Augurite, Up-Grade, Dubious Disc, Metal Coat, and Candy Jar (for Melmetal).
+	- Additional evolution items include the Protector, Black Augurite, Up-Grade, Dubious Disc, and the Metal Coat.
 - The Bottle Cap has been added alongside a Hyper Training feature, acting as effectively a Gold Bottle Cap.
 - The Old Sea Map has been added, giving access to Faraway Island and Mew.
 - The Citrine Pass has been added, allowing access to a new post-game area based on the unused "C" map.

constants/item_constants.asm

@@ -101,6 +101,7 @@ DEF SAFARI_ROCK EQU $16 ; overload
 	const OLD_SEA_MAP	; $5A
 	const UP_GRADE		; $5B
 	const METAL_COAT	; $5C
+	const MYSTERY_BOX	; $5D
 DEF NUM_ITEMS EQU const_value - 1
 
 ; elevator floors use item IDs

data/items/key_items.asm

@@ -92,6 +92,7 @@ KeyItemFlags:
 	dbit TRUE  ; OLD_SEA_MAP
 	dbit FALSE ; UP_GRADE
 	dbit FALSE ; METAL_COAT
+	dbit TRUE  ; MYSTERY_BOX
 	dbit TRUE  ; FLOOR_B2F
 	dbit TRUE  ; FLOOR_B1F
 	dbit TRUE  ; FLOOR_1F

data/items/names.asm

@@ -92,6 +92,7 @@ ItemNames::
 	li "OLD SEA MAP"
 	li "UP-GRADE"
 	li "METAL COAT"
+	li "MYSTERY BOX"
 	assert_list_length NUM_ITEMS
 	li "B2F"
 	li "B1F"

data/items/prices.asm

@@ -92,6 +92,7 @@ ItemPrices::
 	bcd3 0	   ; OLD_SEA_MAP
 	bcd3 3000  ; UP_GRADE
 	bcd3 3000  ; METAL_COAT
+	bcd3 0	   ; MYSTERY_BOX
 	assert_table_length NUM_ITEMS
 	bcd3 0     ; FLOOR_B2F
 	bcd3 0     ; FLOOR_B1F

data/text/item_descriptions.asm

@@ -348,6 +348,11 @@ _OldSeaMapDescription::
 	next "certain island."
 	prompt
 
+_MysteryBoxDescription:: ; GO Description: A mysterious old box. Opening it causes a certain Pokémon to appear for a limited time.
+	text "A mysterious old"
+	next "box."
+	prompt
+
 _HM01Description::
 	text "Cuts using claws,"
 	next "scythes, etc."

data/text/text_2.asm

@@ -1824,3 +1824,13 @@ _BoyGirlText::
     text "Firstly, are you a"
 	line "boy or a girl?"
     done
+
+_MysteryBoxText::
+	text "A mysterious mist"
+	line "billowed out!"
+	prompt
+
+_MysteryBoxCloseText::
+	text "<PLAYER> closed"
+	line "the BOX!"
+	prompt

engine/battle/core.asm

@@ -6191,6 +6191,23 @@ LoadEnemyMonData:
 	ld a, [wLinkState]
 	cp LINK_STATE_BATTLING
 	jp z, LoadEnemyMonFromParty
+	
+	; Upon initiating a battle, check if the Mystery Box has been activated.
+	; ~50% of the time, Meltan will replace what you encounter.
+	ld a, [wMysteryBoxActive] ; Load the box.
+	cp $01 ; Check if it's active.
+	jr nz, .cont ; If not, load a normal Pokemon. I know this looks sort of weird, it's just how it panned out.
+	
+	; This didn't work for some reason. It seems unnecessary, anyway...
+	;call Random
+	;and a
+	;cp 128 ; Compare Random (a) with 128 (b).
+	;jr z, .cont ; If not within range, normal Pokemon appears. 50% chance.
+	
+	ld a, MELTAN ; Meltan is loaded...
+	ld [wEnemyMonSpecies2], a ; Here!
+
+.cont ; Standard loading.
 	ld a, [wEnemyMonSpecies2]
 	ld [wEnemyMonSpecies], a
 	ld [wd0b5], a

engine/debug/debug_party.asm

@@ -161,6 +161,7 @@ DebugSetPokedexEntries:
 	ret
 
 DebugItemsList:
+	db MYSTERY_BOX, 1
 	db BICYCLE, 1
 	db FULL_RESTORE, 99
 	db MAX_REPEL, 99

engine/items/item_effects.asm

@@ -64,7 +64,7 @@ ItemUsePtrTable:
 	dw UnusableItem      ; BIKE_VOUCHER
 	dw ItemUseXAccuracy  ; X_ACCURACY
 	dw ItemUseEvoStone   ; LEAF_STONE
-	dw ItemUseCardKey    ; CARD_KEY
+	dw UnusableItem      ; CARD_KEY
 	dw UnusableItem      ; NUGGET
 	dw UnusableItem      ; WING_FOSSIL
 	dw ItemUsePokedoll   ; POKE_DOLL
@@ -109,6 +109,7 @@ ItemUsePtrTable:
 	dw UnusableItem      ; OLD_SEA_MAP
 	dw ItemUseEvoStone   ; UP_GRADE
 	dw ItemUseEvoStone   ; METAL_COAT
+	dw ItemUseMysteryBox ; MYSTERY_BOX
 	dw UnusableItem      ; FLOOR_B2F
 	dw UnusableItem      ; FLOOR_B1F
     dw UnusableItem      ; FLOOR_1F
@@ -124,6 +125,19 @@ ItemUsePtrTable:
 	dw UnusableItem      ; FLOOR_11F
 	dw UnusableItem      ; FLOOR_14F
 
+ItemUseMysteryBox:
+	; Mystery Box can't be used in battle.
+	ld a, [wIsInBattle]
+	and a
+	jp nz, ItemUseNotTime
+	; Sets a variable in WRAM that'll trigger a Meltan wild encounter.
+	; Handled in engine\core.asm
+	ld a, $1
+	ld [wMysteryBoxActive], a
+	ld hl, MysteryBoxText ; Simple text is shown. Ambiguous to the user, identical to GO.
+	call PrintText
+	jp TextScriptEnd
+
 ItemUseBall:
 
 ; Balls can't be used out of battle.
@@ -1585,55 +1599,55 @@ ItemUseXAccuracy:
 
 ; This function is bugged and never works. It always jumps to ItemUseNotTime.
 ; The Card Key is handled in a different way.
-ItemUseCardKey:
+;ItemUseCardKey:
-	xor a
+;	xor a
-	ld [wUnusedD71F], a
+;	ld [wUnusedD71F], a
-	call GetTileAndCoordsInFrontOfPlayer
+;	call GetTileAndCoordsInFrontOfPlayer
-	ld a, [GetTileAndCoordsInFrontOfPlayer]
+;	ld a, [GetTileAndCoordsInFrontOfPlayer]
-	cp $18
+;	cp $18
-	jr nz, .next0
+;	jr nz, .next0
-	ld hl, CardKeyTable1
+;	ld hl, CardKeyTable1
-	jr .next1
+;	jr .next1
-.next0
+;.next0
-	cp $24
+;	cp $24
-	jr nz, .next2
+;	jr nz, .next2
-	ld hl, CardKeyTable2
+;	ld hl, CardKeyTable2
-	jr .next1
+;	jr .next1
-.next2
+;.next2
-	cp $5e
+;	cp $5e
-	jp nz, ItemUseNotTime
+;	jp nz, ItemUseNotTime
-	ld hl, CardKeyTable3
+;	ld hl, CardKeyTable3
-.next1
+;.next1
-	ld a, [wCurMap]
+;	ld a, [wCurMap]
-	ld b, a
+;	ld b, a
-.loop
+;.loop
-	ld a, [hli]
+;	ld a, [hli]
-	cp -1
+;	cp -1
-	jp z, ItemUseNotTime
+;	jp z, ItemUseNotTime
-	cp b
+;	cp b
-	jr nz, .nextEntry1
+;	jr nz, .nextEntry1
-	ld a, [hli]
+;	ld a, [hli]
-	cp d
+;	cp d
-	jr nz, .nextEntry2
+;	jr nz, .nextEntry2
-	ld a, [hli]
+;	ld a, [hli]
-	cp e
+;	cp e
-	jr nz, .nextEntry3
+;	jr nz, .nextEntry3
-	ld a, [hl]
+;	ld a, [hl]
-	ld [wUnusedD71F], a
+;	ld [wUnusedD71F], a
-	jr .done
+;	jr .done
-.nextEntry1
+;.nextEntry1
-	inc hl
+;	inc hl
-.nextEntry2
+;.nextEntry2
-	inc hl
+;	inc hl
-.nextEntry3
+;.nextEntry3
-	inc hl
+;	inc hl
-	jr .loop
+;	jr .loop
-.done
+;.done
-	ld hl, ItemUseText00
+;	ld hl, ItemUseText00
-	call PrintText
+;	call PrintText
-	ld hl, wd728
+;	ld hl, wd728
-	set 7, [hl]
+;	set 7, [hl]
-	ret
+;	ret
 
 INCLUDE "data/events/card_key_coords.asm"
 
@@ -2980,3 +2994,7 @@ CheckMapForMon:
 	jr nz, .loop
 	dec hl
 	ret
+
+MysteryBoxText:
+	text_far _MysteryBoxText
+	text_end

engine/menus/item_descriptions.asm

@@ -198,6 +198,8 @@ ItemDescriptionPointers:
 	text_end
 	text_far _MetalCoatDescription
 	text_end
+	text_far _MysteryBoxDescription
+	text_end
 	text_far _HM01Description
 	text_end
 	text_far _HM02Description

engine/overworld/clear_variables.asm

@@ -10,7 +10,7 @@ ClearVariablesOnEnterMap::
 	ldh [hJoyReleased], a
 	ldh [hJoyHeld], a
 	ld [wActionResultOrTookBattleTurn], a
-	ld [wUnusedD5A3], a
+	ld [wMysteryBoxActive], a
 	ld hl, wCardKeyDoorY
 	ld [hli], a
 	ld [hl], a

ram/wram.asm

@@ -1953,7 +1953,7 @@ wCurrentBoxNum:: db
 ; number of HOF teams
 wNumHoFTeams:: db
 
-wUnusedD5A3:: db
+ds 1 ; was wUnusedD5A3, removed when putting the Mystery Box in.
 
 wPlayerCoins:: ds 2 ; BCD
 
@@ -2177,7 +2177,11 @@ wDungeonWarpDestinationMap:: db
 ; which dungeon warp within the source map was used
 wWhichDungeonWarp:: db
 
-wUnusedD71F:: db
+; Used for Meltan implementation. Replaced unused Card Key function.
+; When byte is $01, Meltan has a chance to replace a Pokemon that appears.
+	; $00 - Not Active
+	; $01 - Active
+wMysteryBoxActive:: db
 
 	ds 8
 

scripts/SafariZoneEastRestHouse.asm

@@ -21,42 +21,43 @@ SafariZoneRestHouse3Text3:
 	text_end
 
 SafariZoneRestHouse3Meltan:
-; meltan guy
+; Meltan Guy
+; Originally, he was just going to give Meltan.
+; But later on, we added the Mystery Box from GO for something more accurate, and for a possible Living Dex.
 	text_asm
-	ld a, [wd72e]
-	bit 0, a ; got meltan?
-	jr z, .giveMeltan
 	CheckEvent EVENT_GOT_MELTAN
-	jr nz, .MeltanInfo
+	jr nz, .got_item
-	ld hl, .MeltanGuyText
+	ld hl, MeltanGuyText
 	call PrintText
-	jr .done
+	lb bc, MYSTERY_BOX, 1
-.giveMeltan
+	call GiveItem
-	ld hl, .MeltanGuyText
+	jr nc, .bag_full
+	ld hl, ReceivedBoxText
 	call PrintText
-	lb bc, MELTAN, 5
 	SetEvent EVENT_GOT_MELTAN
-	call GivePokemon
-	jr nc, .done
-	ld a, [wSimulatedJoypadStatesEnd]
-	and a
-	call z, WaitForTextScrollButtonPress
-	call EnableAutoTextBoxDrawing
-	ld hl, .MeltanInfoWithBlackjackAndHookers
-	call PrintText
-	ld hl, wd72e
-	set 0, [hl]
 	jr .done
-.MeltanInfo
+.bag_full
-	ld hl, .MeltanInfoWithBlackjackAndHookers
+	ld hl, BoxNoRoom
+	call PrintText
+	jr .done
+.got_item
+	ld hl, MeltanInfo
 	call PrintText
 .done
 	jp TextScriptEnd
 
-.MeltanInfoWithBlackjackAndHookers
+MeltanGuyText:
+	text_far _MeltanGuyText
+	text_end
+
+MeltanInfo:
 	text_far _MeltanInfo
 	text_end
 
-.MeltanGuyText
+ReceivedBoxText:
-	text_far _MeltanGuyText
+	text_far _ReceivedBoxText
+	text_end
+	
+BoxNoRoom:
+	text_far _BoxNoRoom
 	text_end

text/SafariZoneEastRestHouse.asm

@@ -18,21 +18,57 @@ _SafariZoneRestHouse3Text3::
 	done
 
 _MeltanGuyText::
-	text "I found a lost"
+	text "Sheesh! This old"
-	line "#MON. It seems"
+	line "BOX I found is"
-	cont "to be looking"
+	cont "heavy."
-	cont "for its friends."
 	
-	para "Could you take"
+	para "Mind taking it"
-	line "care of it, kid?"
+	line "off my hands,"
+	cont "kid?"
 	
 	prompt
 
 _MeltanInfo::
-	text "My sources say it's"
+	text "I saw a strange"
-	line "called MELTAN."
+	line "#MON coming"
+	cont "out of that"
+	cont "thing."
 	
-	para "It's never seen in"
+	para "It's so creepy!"
-	line "KANTO..."
 	
 	done
+
+_BoxNoRoom::
+	text "No room? Ugh,"
+	line "kids these"
+	cont "days..."
+	
+	done
+
+_ReceivedBoxText::
+	text "<PLAYER> received"
+	line "@"
+	text_ram wStringBuffer
+	text "!@"
+	text_end
+
+; Old Meltan Guy text.
+;_MeltanGuyText::
+;	text "I found a lost"
+;	line "#MON. It seems"
+;	cont "to be looking"
+;	cont "for its friends."
+;	
+;	para "Could you take"
+;	line "care of it, kid?"
+	
+;	prompt
+
+;_MeltanInfo::
+;	text "My sources say it's"
+;	line "called MELTAN."
+	
+;	para "It's never seen in"
+;	line "KANTO..."
+	
+;	done