Gen1Arena

2D image backdrops behind Gen1Recomp battles
Selected by map, tileset and encounter kind. Works in both OG (160x144) and WIDE (304x144) layouts.

Every image on this page is a file out of assets/backdrops/, scaled by a whole number and otherwise untouched.

By Wild.

Credit -- required

None of the art in this repository was drawn for this mod. Every backdrop under assets/backdrops/ comes from the Battle Backgrounds Patch FR for Pokemon FireRed. Its authors ask for credit whenever the pack is used, and that request is the condition this repository ships under:

LibertyTwins · princess-phoenix · carchagui · aveontrainer · WesleyFG · kWharever · worldslayer608 · knizz

If you use, fork or restyle this mod, or lift a single backdrop out of it, carry those names with it. What this mod adds is the selection logic and three mechanical passes -- a palette correction, a crop to the engine's two layouts, and per-town roof recolours. The composition, linework and colour choices in every scene are theirs. See CREDITS.md for the full statement.

Only the subset of backdrops the mod actually loads is committed here, not the whole source pack -- see What art ships.

Note also that Gen1Recomp's mod rules forbid shipping ROM-derived content in a mod. Some of this pack is original fan art and some is FireRed-derived, and I can't tell which is which from the files.

Pokemon Red / Blue / FireRed are Nintendo / Creatures / GAME FREAK. This is an unofficial fan mod with no affiliation or endorsement.

The two layouts

The engine draws battles at either 160x144 or 304x144, and every backdrop ships cropped for both.

What got mapped

Slot	Source	FireRed scene
default, field, safari	0 Grass	Grass
forest	1 Forest	Forest
cave	7 Cave	Cave
plateau	6 Mountain	Craggy
port	2 Beach	Sand
sea, deck	4 Sea	Sea
lake	5 Lake	Pond
water_cave	3 Underwater	Underwater
trainer_indoor	8 Lab	Indoor Trainer
trainer, trainer_field	9 Route	Outdoor Trainer
trainer_gym	11 Neutral	Gym Trainer
gym, leader	12 Gym	Gym Leader
town, trainer_town	13 Town	Pokemon Tower
giovanni	14 Snow	Giovanni
lorelei	15 Snow Cave	Lorelei
bruno	16 Snow Mountain	Bruno
agatha	17 Desert	Agatha
lance	18 Volcano	Lance
champion	19 Space	Champion
indoor, museum, club, mansion, ship, tower	10 Indoors	Trainer Tower

The right-hand column is what FireRed itself uses each scene for, per Backgrounds Table.txt in the source pack. The patch we took the art from remaps most of them onto the Gym scene -- gym trainers, and all four Elite Four. These assignments restore the vanilla split instead, which is what the art was drawn for.

Bosses are matched on trainer class, not map, so Giovanni keeps his scene in all three of his fights (Rocket Hideout, Silph 11F, Viridian Gym). A boss scene outranks the room, the same way water does -- Agatha's room carries the CEMETERY tileset and she still gets her own backdrop rather than the tower's. OPP_RIVAL3 is the Champion and nothing else; RIVAL1 and RIVAL2 stay on whatever room they are fought in.

Unused: none. All 20 backgrounds have a home.

tower deliberately diverges from FireRed. Slot 13 is FireRed's Pokemon Tower scene, but the patch author drew it as an outdoor town view -- a paved plaza under open sky, for a battle on the fourth floor of a building. The tower uses the Indoors art instead, under GRAYMON; slot 13 keeps the town slots it genuinely suits.

Because place outranks kind, a slot like trainer only fires on a tileset with no art of its own. That is why Route is also registered as trainer_field: wild battles on a route get Grass, trainer battles on the same route get Route.

indoor is the fallback for anything inside a building, so an unmapped interior tileset gets a room rather than a grass field. Only OVERWORLD, PLATEAU, SHIP_PORT, FOREST, CAVERN and UNDERGROUND are treated as not-a- building; everything else lands on indoor. The SS Anne interior (SHIP) uses it too. port (Vermilion dock) uses Beach.

Resolved situations

Situation	Backdrop
wild in route grass	Grass
trainer on a route	Route
wild or trainer in Viridian Forest	Forest
wild or trainer in a cave	Cave
trainer in a gym	Gym
trainer in a town	Town
surfing or fishing on the open coast	Sea
surfing or fishing on inland water	Lake
surfing or fishing inside a cave	Underwater
fishing, anywhere	Lake
swimmer trainer	whichever water they are on
Snorlax / the birds / Mewtwo	whatever room they are in
Safari Zone	Grass
SS Anne cabins and corridors	Indoors
SS Anne decks (incl. the rival fight)	Sea
Vermilion dock	Beach
Pokemon Tower	Neutral
Rocket Hideout / Silph	Lab
Indigo Plateau	Mountain

Auditing the whole game

Run the game in developer mode (POKEPORT_DEV=1, or --developer), turn on DIAGNOSTIC and load a save. (DIAGNOSTIC only logs -- it does not change what you see. The magenta test field is the separate FIELD TEST row.) At startup the mod walks every map in data.maps and logs what battles it can host and what backdrop it resolves to:

--- gen1arena audit: N maps ---
    flags: G=grass W=water T=trainers S=static
  CERULEAN_CAVE_1F     CAVERN      GW-S -> cave
  SS_ANNE_BOW          SHIP        --T- -> deck
  OAKS_LAB             LAB         ---- -> lab
--- no unmapped tilesets, no missing art ---

• G / W -- rolled grass / water encounters, from data.encounters
• T -- trainer NPCs, map objects carrying trainerClass
• S -- static wild encounters, objects carrying pokemon (Snorlax, the birds, Mewtwo, the Vermilion Machop)

Every map is listed, not just ones with those flags, because a map can host a battle with none of them: the rival in Oak's Lab, Oak in Pallet Town and the Chief in Celadon are script start_battle rows with no trainer object behind them. Those are exactly the maps an encounter-driven audit would miss.

Each row is also checked against the art on disk, so a slot that resolves but has no PNG is flagged NO ART FOR SLOT rather than silently falling back.

Where the audit goes

The engine's Logger only prints and keeps the last 200 lines, and Kanto has more maps than that -- so the full table would scroll itself away, and on iOS stdout is nowhere you can reach anyway. Instead:

• Full table -> a file, written through mod storage: mod_storage/<gameVersion>/<playthroughId>/gen1arena/audit.bin under the LOVE save directory for identity pokemon-love2d:

  • Windows: %APPDATA%\LOVE\pokemon-love2d\
  • macOS: ~/Library/Application Support/LOVE/pokemon-love2d/
  • Linux: ~/.local/share/love/pokemon-love2d/

  Despite the .bin extension it is plain text -- that suffix is just how mod storage tags opaque values. Open it in any editor.

• Problems only -> the log. Unmapped tilesets and missing art always fit well inside 200 lines, so if the audit is clean you will see one line saying so.

Storage needs an identified playthrough, so load a save first; running the audit from the title screen will report not_in_playthrough.

audit.bin is the artefact to attach when reporting a gap.

On Gold, Silver and Crystal

The mod runs on the Gen 2 carts too, and the backdrops there are Johto's own. 126 files under assets/backdrops/og/gen2/, mapped the same way Kanto's are: by the cart's tileset and landmark rather than by a list of map ids, so a map the table has never heard of still lands on something sensible instead of nothing.

Gold picks a battle's scene from a different set of facts than Red does, so the lookup is its own rather than the Kanto one with names swapped. Tileset first, then the landmark, then the trainer's class for the ones that have a scene of their own — a gym leader is fought in their gym, the champion at the Plateau. Sea and lake are separated by the map's fishing group — OCEAN, WHIRL_ISLANDS, QWILFISH, REMORAID are the sea, LAKE, POND, GYARADOS, DRATINI inland — and by landmark where the group is SHORE, which is also what a header with no group says.

Everything else behaves as it does on Red: the same two crops, the same palette correction, the same BATTLE SCENES row to turn the whole thing off. And two rows of Gold's own, and two of the cart's settings it follows:

• TIME OF DAY (on): the picture goes through the map's own night and morning, fitted to the cart's DAY and NITE palettes for that map, so a field at midnight is that field's night rather than a blue wash. Outdoors only.
• CLEAR BOXES (OFF to 100%): the bottom strip's boxes lay their paper at the strength picked; border and ink stay. Boxes over the HUD and the pics keep theirs.
• With the cart's BATTLE BG on WORLD, the picture still goes into the bars as far as it reaches (on the classic layout, the side bars of any screen wider than the battle, top to bottom), and the world fills everything else, where black used to be. EDGE TO EDGE off leaves all of the surround to the world.
• With BATTLE HUD on EXTENDED, a wide battle's HUD and bottom strip sit above and below the field; only the side bars are filled, so nothing is painted over them.

tools/audit_gen2_arena.py <pokecrystal> replays every Crystal map header through these tables and prints where each kind of place lands.

On FireRed, LeafGreen and Emerald

This is where the art comes from — every picture is from the Battle Backgrounds Patch FR, 240x112 FireRed battle-field art — and on a Gen 3 boot it goes back onto that field 1:1, through BattleBg.draw, the one call that paints a GBA battle's background. The arm is gen3.lua; main.lua hands over to it before requiring anything.

• Which picture starts from the cart's own terrain (grass, long grass, sand, water, pond, mountain, cave, building, or the cart's scene for a gym, a leader or an Elite Four room) and the map narrows it: Viridian Forest and Petalburg Woods are the forest, Icefall and Shoal Cave the ice cave, Mt. Ember and the Magma Hideout the volcano, the Pokémon Tower and Mt. Pyre the Tower, the S.S. Anne and the S.S. Tidal the ship, Route 111's sand the desert, water underground the water cave, and a Kanto town its own roof colours. A trainer battle takes the trainer's version where one is drawn.
• No picture — the cart's own background — for underwater, link battles, Route 113's ash, and Emerald's own scenes: the Battle Frontier, the legendaries, the Hoenn Elite Four, and Wallace's room, which is under water.
• No platforms over it. The cart keeps its platform ovals as layers for the intro slide, but they are opaque tiles of its own ground, not cut-outs, so they would print the vanilla ground over the picture. The art's own ground carries the Pokémon, as it does on Red and Gold.
• The fit: the middle 240 columns of the wide art, the picture's ground on the field's bottom edge, its top rows mirrored upward where the art runs eight short. Nothing is scaled.

Anything that fails in that draw is the cart's background, said once in the log, and never an error in the battle's own draw.

Ruby and Sapphire, which the engine runs in beta, are Gen 3 boots too and get the same: the terrain picks the picture, and their Hoenn maps carry the same names Emerald's do.

Town recolours

Taken from the engine's own overworld colouring, not invented. world.roofByMapIndex in data/palettes_gbc.lua is indexed by map index (the eleven city maps, 0..10) and holds exactly two colours per town -- a roof light and a roof dark:

0 Pallet     white / grey        6 Celadon    mint / green
1 Viridian   green               7 Fuchsia    magenta / rose
2 Pewter     blue-grey stone     8 Cinnabar   red
3 Cerulean   sky blue            9 Indigo     violet
4 Lavender   purple             10 Saffron    yellow / gold
5 Vermilion  orange

That is the entire difference between one Kanto town and the next in the GBC overworld: the roofs change and nothing else does. Grass stays green, water stays blue, paths and stone stay as they are. So that is what these recolours do. Earlier attempts at a full-scene tint were inventing a difference the game does not have.

The same plaza in all ten towns, cropped to the roofline.

• Town maps -- the art's two roof browns are remapped onto that town's roof pair by luminance. The mask is hue+saturation: the only saturated warm colours in the town art are the roofs (hue 20/28, sat ~0.7), while tree green (146) and water blue (195/228) are far outside it and every structural colour sits below 0.35 saturation.

Walls rotate to the town's hue. The floor, the court lines and the Poke Ball are byte-identical in every one.

• Gyms -- walls only, rotated to the town's roof hue. The floor, court lines and Poke Ball are byte-identical in every gym, so the ball reads as the same ball everywhere. The gym mask is by hue, not position: the wall's bottom edge is diagonal, so a positional mask cut a hard band across the floor. Wall planks sit at hue 324-360/0-5 and the floor's orange at 24-31. The y<62 guard exists for one reason only -- the Poke Ball's red is the same red as the wall.
• Interiors are untouched. A Pokemon Center looks the same in every city.

Gym leaders take their town's colour; Giovanni, the Elite Four and the Champion keep their own scenes.

Regenerate with recolor.py.

The Pokemon Tower

FieldDefaults routes the tower by tileset, not by map: byTileset = { CEMETERY = "GRAYMON" }. So it does not wear Lavender's palette at all -- it wears GRAYMON, and every CEMETERY map gets it. That makes it a change to the base tower slot rather than a per-town variant.

GRAYMON is white / (214,132,181) / (123,107,148) / black. Used whole it comes out pink: its midtone is a dusty rose and most of the art's luminance lands on it. Only the third stop -- the grey-violet -- gives the drained look the name promises, so that is the one used, at 0.80 strength with a 0.85 dusk.

This is an interpretation of the palette, not a transcription. The game applies all four stops. Picking one out of four is a judgement call.

Base art: 10 Indoors, not slot 13. The tower is an interior and slot 13 is an outdoor plaza with sky. Under GRAYMON the Indoors art reads as a pillared hall, which is what the room is. The cost is that the tower and every Pokemon Center share one image, separated only by the GRAYMON pass -- visible in tower_final.png, and a fair trade.

Per-map overrides

A few maps are the wrong shape for their tileset. The S.S. Anne's open decks carry the SHIP tileset along with the cabins, so a tileset-only rule stands you in a panelled room while you are outside on the sea. MAP_SLOT in main.lua is checked before the tileset and fixes those by map id:

SS_ANNE_BOW          -> deck      foredeck, and the rival fight
SS_ANNE_3F           -> deck      top-deck walkway
VERMILION_DOCK       -> port
OAKS_LAB             -> indoor    carries the DOJO tileset
CINNABAR_GYM         -> gym       carries FACILITY
SAFFRON_GYM          -> gym       carries FACILITY
SILPH_CO_11F         -> indoor    carries INTERIOR
CELADON_MART_ROOF    -> town      open air on an interior tileset
CELADON_MANSION_ROOF -> town      same

Every one of these was found by running the audit against the real map data, not guessed. OAKS_LAB mattered most: it uses the DOJO tileset, so the rival fight that opens the game was resolving to a gym. Blaine and Sabrina were showing Silph Co.'s interior because their gyms carry FACILITY.

Two SHIP-tileset maps are not ships at all -- CERULEAN_BADGE_HOUSE and FUCHSIA_GOOD_ROD_HOUSE -- which is harmless only because ship uses the Indoors art. It would have broken if ship were the sea, which is the version of this that shipped in 0.2.1.

SS_ANNE_STERN does not exist; that was a guess of mine, now removed.

Water

Which water you are on, not what you are doing on it -- so surfing and fishing the same water get the same backdrop, and fishing from a boat no longer shows a lake on the open ocean.

open coast   -> Sea
inland       -> Lake
inside a cave -> Underwater

Water outranks a town's recolour as well as the tileset. The eleven city maps carry OVERWORLD and resolve to town, so until 0.18.1 surfing off Cinnabar or fishing at Vermilion came up against the town's rooftops -- the town variant answered before the water rule was reached.

The cave case comes first: Seafoam and Cerulean Cave have no sky, and the Sea backdrop is mostly sky.

Lookup order

Wild battle in a cave: wild_cave -> cave -> wild -> default.

Kinds: wild, trainer, safari, link. Places: field, plateau, forest, cave, tower, mansion, gym, club, facility, ship, lab, museum, indoor.

Palette correction

The FireRed art is authored for a GBA and reads washed out next to ADVANCED's GBC sprites. Measured over every pixel of all 20 backgrounds against the 446 colours in data/palettes_gbc.lua:

	mean saturation	mean value
FR pack, as shipped	0.372	0.713
ADVANCED (pokered-gbc)	0.674	0.771

So the gap is chroma, not brightness -- a brightness/contrast tweak would not have fixed it. palettize.py applies a per-image saturation power curve fitted so each image lands on its own target, then quantises every channel onto the GBC's 5-bit ladder. Working on the palette rather than the pixels keeps the flat pixel-art blocking intact.

Two things it deliberately does NOT do:

• It does not push everything to one saturation number. Grey interiors (Indoors, Lab) get a gentle washout fix capped well below the mean; a lab wall is supposed to be grey.
• It does not snap to the nearest SuperPalette colour. That was tried first and was wrong: nearest-neighbour in CIELAB does not preserve luminance ORDER, so Cave's mid-dark rock was pulled up while its darkest shade was pulled to pure black, drawing hard rims round the cave mouths. Quantising is monotonic per channel and cannot do that.

Dark scenes (Cave, Volcano) get a reduced chroma boost and a value lift, since pushing them further made them darker -- the direction that turns a Gen 1 back sprite into a silhouette.

Re-run: python3 palettize.py <FR Resources> corrected/ then python3 convert.py corrected/ assets/backdrops/.

Geometry

Sizes are read from engine source, not guessed:

• og/*.png -- 160x144, battlefield is the top 96 rows (drawClassic scissors mon pics to y < 96)
• wide/*.png -- 304x144, battlefield is the top 104 rows (WideBattle.FIELD_BOTTOM = 104)

Rows below the battlefield sit under the message window, and the files fill them flat. The mod does not show that flat band: when a picture loads, the band is replaced with the ground just above it, mirrored down, so the picture runs to the bottom of the screen the way field does -- in the side bars beside the message box, and on the field whenever no box is up. Nothing is resampled -- a backdrop pixel is exactly one sprite pixel. The price is cropping: the source art is a 240x112 GBA field, so OG shows its middle 160 columns, and WIDE mirror-pads 32 columns onto each side. The mirror seam is visible on default/field where a tree sits near the right edge.

To re-cut with different crops, edit convert.py and re-run.

Indoors is indoors

FireRed picks a scene by terrain, and inside a building that means: a wild battle gets the generic Indoors scene, a trainer battle gets the Indoor Trainer scene. The FACILITY, LAB, INTERIOR, HOUSE, MART, POKECENTER, LOBBY, GATE and FOREST_GATE tilesets all now resolve to one indoor place, and the split falls out of the lookup for free because trainer_indoor outranks indoor.

That retired the separate lab and facility slots. They were showing the Indoor Trainer scene to wild encounters in Pokemon Mansion and the Power Plant -- the only two buildings in Kanto with wild battles, so the only two places the mistake was visible.

Still open

• The sea/inland split is hand-classified. Nothing in the map data distinguishes a sea tile from a pond tile, so OCEAN_MAP in main.lua is a hand-classified list from Kanto's geography: Pallet, Vermilion and its dock, Cinnabar, Fuchsia, and Routes 12, 13, 19, 20 and 21. Everything else is inland. If a route looks wrong, it is one line.

• Underwater art is unused. Gen 1 has no Dive; the engine rolls exactly three terrains (grass, water, indoor) plus fishing pools. There is nowhere to put it.

• Back-sprite contrast -- fixed in 0.19.0 by MON PAPER, on by default. Gen 1 pics are matted: the extractor floods colour 0 in from the edge of the pic and turns it transparent, and because the flood stops only at ink it pours through any gap in a mon's outline and hollows out the body behind it. Against the white field that is invisible; against a backdrop it is a window, and a pale mon -- Mew's back pic keeps 145 of the 400 pixels in its own bounding box -- reads as a bare outline with the scenery showing through. MON PAPER fills the pic's own content box with the field shade before the engine draws it, which is the composition the Game Boy showed. Only pics that actually lost something get it: four-shade art with more than 35% of its content box given over to transparency the mon's own ink is on both sides of, in both axes -- a window through the body rather than the space around it. A sprite mod's true-colour replacement carries its own alpha and is left alone, so a Crystal front and a vanilla back in the same battle are each treated correctly.

  That test used to be plain emptiness -- how much of the bounding box was not ink -- and it read an awkward shape as a damaged one. A Crystal Koffing with its gas plume out measures 0.51 empty on three frames of nine and 0.26 on the other six, so a solid, undamaged sprite crossed a 0.30 line three times per animation cycle and the paper blinked on and off behind it. By enclosure every frame of it scores 0.00 to 0.05. The line at 0.35 is set off the art: across all 8,563 images in that sprite pack the highest is 0.282, an Unown O, which is a ring and honestly has a hole in it, while a pic the flood reduced to a bare outline is 0.47 to 0.64.

• Palette modes. Backdrops bypass the palette bake, so they do not shift with COLORS. In OG / OG INV / CLASSIC you get full-colour GBA art behind four-shade sprites. Check it in ADVANCED first.

• White flashes. Battle intro wipes and the hit-flash overlay still paint white, now over a backdrop instead of a white field.

What art ships

The sheets on this page are redrawn from the committed art by

python3 tools/make_showcase.py          # every sheet
python3 tools/make_showcase.py towns    # ... or just the ones named

It needs Pillow, and fetches its label font from Google Fonts once into tools/.cache/, which is not committed. Nothing in a sheet is drawn, composited or touched up -- each tile is a crop of a file under assets/backdrops/ at a whole-number scale.

assets/backdrops/ holds only the images the mod can actually load, not the whole generated set and not the source pack. Two layouts, og/ and wide/, each carrying:

• the 31 base slots at the top level -- the slot table above, one PNG each
• <town>/town.png for the ten town maps: Pallet, Viridian, Pewter, Cerulean, Vermilion, Celadon, Fuchsia, Cinnabar, Saffron and Lavender
• <town>/gym.png and <town>/trainer_gym.png for the eight towns with a gym -- everywhere except Pallet and Lavender, which have none
• indigo/plateau.png, the only map Indigo owns

Everything else recolor.py emits is dropped, because the lookup in pickBackdrop can never reach it and the file is byte-identical to the one it would fall back to:

Dropped	Falls back to	Same image?
<town>/trainer_town.png	<town>/town.png	yes -- the town pass does not treat them differently
<town>/leader.png	<town>/gym.png	yes -- leader_gym is never a filename, so the leader lands on the gym art either way
<town>/plateau.png (all but Indigo)	--	unreachable; no other town has a PLATEAU map
<town>/gym.png, trainer_gym.png for Pallet, Lavender, Indigo	--	unreachable; those three have no gym
<town>/tower.png	root tower.png	no, and that is the point. The tower wears GRAYMON by tileset, not a town's roofs. Older builds emitted a Lavender-tinted tower.png that shadowed it; recolor.py no longer generates one

Re-running recolor.py will put the dropped files back. They are harmless -- they resolve to the same picture -- but they do not need committing. The one exception is <town>/tower.png: the current recolor.py does not emit it, and it should not come back.

Install

1. Download gen1arena-<version>.zip from the latest release -- the file under Assets, not Source code.
2. In the launcher's MODS tab, Import mod .zip and pick it. Do not unzip it first. Or install Gen1Arena from a mod index in the same tab.
3. Start the game. The mod is on as soon as it is installed; nothing else needs turning on.

The same zip covers every game: Red, Blue, Yellow, Gold, Silver, Crystal, FireRed, LeafGreen and Emerald (and Ruby and Sapphire, in beta). Gen1Wild UI users already have it -- it is one of the bundle's modules, so do not install it a second time.

Finding the options. They are on the mod's own page, not in the game's own option list: START -> MODS -> Gen1Arena -> OPTIONS.. The path is the same on every game. No OPTIONS.. row on that page means the mod did not load: VIEW ERROR.. there, or the manager's errors tab (ERRS, or ERRORS on FireRed, LeafGreen and Emerald), says why.

0.37.0 and 0.37.1 on FireRed, LeafGreen and Emerald: the release zip was missing the GBA half of the mod (gen3.lua), so it did nothing there, had no options row, and reported no error either. Install 0.38.0 or newer. Red, Blue, Yellow, Gold, Silver and Crystal were not affected, and nor was Gen1Wild UI.

On FireRed, LeafGreen and Emerald (and Ruby and Sapphire, which the engine runs in beta) there is one row:

• BACKDROPS -- on/off

On Red, Blue, Yellow, Gold, Silver and Crystal:

• BACKDROPS -- on/off
• MON PAPER -- lay the field shade back under a pic the matte hollowed out, so a pale mon is not a window onto the backdrop. Off leaves the pic exactly as the engine hands it over
• PIC CUTOUT -- cut the cart's mon and trainer pics out of their baked white square, so there is no box over the backdrop
• EDGE TO EDGE -- run the picture out into the bars around the battle; off leaves them black

and on Gold, Silver and Crystal also:

• CLEAR HUD -- names, levels and HP bars straight on the picture instead of each on its own white block
• TIME OF DAY -- the backdrop follows the clock: Gold's night and morning palettes outdoors
• CLEAR BOXES -- OFF to 100% in steps of 10: how much of the picture shows through the battle's text and menu boxes

and two more in developer mode only (POKEPORT_DEV=1, or --developer, which the engine resolves once and hands each mod as mod.developer):

• DIAGNOSTIC -- logging and the startup audit; changes nothing on screen
• FIELD TEST -- paints the battlefield flat magenta instead of the backdrop, to tell "patch never ran" apart from "patch ran, image lost"

Those two are maintenance tools rather than settings, and the second is a trap on a shipped cart: the row does not say what it does, and finding out leaves every battle magenta until you find the row again. Outside developer mode they are not offered and not read, so a value left set in an older install cannot strand anyone.

If it is still white

Run the game in developer mode (POKEPORT_DEV=1, or --developer) so the row is offered, turn on the mod's FIELD TEST row and start a battle:

• Magenta field -- the patch is running and the backdrop is being lost downstream (palette pass or canvas ordering). Tell me which layout and which COLORS mode.
• Wrong background everywhere -- DIAGNOSTIC also logs each tileset the first time a battle starts on it, as tileset SHIP -> ship. An (unmapped, using default) line means that tileset needs a row in TILESET_SLOT.
• Still white -- the patch never fired. Check the log for [gen1arena] patched battle draw; its absence is the signal.