Extras

OPTIONS → Extras holds optional HUD and effect mods from the CTR-ModSDK modules, as High Octane ships them. Each row is saved in config.ini under [Extras], is visual only, and applies at once, except Cyan Super Pads, which applies at the next track load.

Row	Key	Default	What it does	Code
Reserves Meter	`reserves_meter`	On in the Archipelago build, off in vanilla	A 49×3 bar under the powerslide bar showing the boost reserves you hold, in 1P races and crystal challenges. Red, yellow, green by amount; blue once it overruns the bar; purple once the value has wrapped past 0x7FFF and no longer drains ("Saffi fire").	`UI_DrawReservesMeter` in `game/UI/UI_Meter.c`, maths in `ap/ap_reserves_meter_logic.h`
Keep Reserve Fire	`reserve_fire`	Off	While a driver holds reserves, powerslide fire stays visible. Retail kills it after two frames or hides it for the visibility cooldown, so chained slides with no start boost show no fire.	`VehFire_KeepReserveFire` in `game/Vehicle/VehFire.c`
Blue Fire At USF	`blue_fire`	Off	Player 1's exhaust turns blue at Ultimate Speed Fire, as in Nitro-Fueled.	`game/VehBlueFire.c`
Slide Meter Gradient	`slide_meter_colours`	Off	The powerslide bar fades green to yellow as it fills, then orange to red across the boost window, instead of flat green then red.	`UI_DrawSlideMeter`, maths in `include/ctr_extras.h`
Colour Filter	`colour_filter`	Off	Greyscale, sepia, negative, vignette, or a protanopia or deuteranopia correction, on top of any screen filter.	SCREEN-FILTERS.md, `platform/native_renderer.c`
Cyan Super Pads (Next Load)	`super_pad_colour`	Off	Super turbo pads are drawn cyan, as in Nitro-Fueled. With the all-super-turbo-pads cheat every pad is cyan.	`game/LevSuperTurboPads.c`, the shader in `platform/native_renderer.c`, rules in `include/ctr_extras.h`

Decisions

Options, default off. The retail look stays the default. The reserves meter defaults on in the Archipelago build only because that build always drew it.
One implementation for both builds. The Archipelago build's reserves meter, fire tweak and blue fire are the same code as these rows:
The reserves meter draws whenever the option is on. The speed readout under it is Archipelago only.
The fire tweak reads the option. With no config.ini, the Archipelago build honours hud_reserves_fx=1 in ap-config.txt (AP_HudReservesFx, same precedence as map_flash).
The blue palette has one writer, VehBlueFire_Tick, run every frame from MainMain. It turns blue when the option or the Archipelago Progressive Boost capstone asks (AP_BlueFireWanted), so the two never fight over the same VRAM cells.
The fire tweak is the whole ModSDK tweak: it stops the visibility-cooldown hide and keeps a powerslide's first flame alive past two frames.
USF is detected from the driver's constants: fire speed cap above the sacred-fire cap, the test VehFire_Increment uses, not the ModSDK module's fixed 0x4800.
Palettes are only written while a race is loaded. Hubs and menus use the same VRAM cells, so outside a race the palette state is dropped and rewritten at the next race (ap/ap_blue_fire_logic.h).
Cyan pads are found from the level's data. Ordinary and super pads share one animated arrow texture, so it can't simply be recoloured. A pad is:
an invisible trigger quad whose terrain byte has the turbo or super turbo bit;
a visible overlay quad covering at least 98% of the trigger, within 30 units of its height, with a 10-frame animated texture;
often a non-animated road quad with the same footprint under it.

So a pad animation is an animated texture on a quad covering 90% or more of any pad trigger, and a super-pad face is a face showing a pad animation on a quad that overlaps a super trigger at its height. This needs no per-track exceptions (Cortex Castle's wooden tiles under super triggers carry no pad animation). - The colour travels in the palette word's top bit. Each super-pad face gets a copy of the pad animation whose texture layouts set bit 15 of the palette word, which real PSX data never sets. The shader clears it before the palette lookup and recolours the texel from its brightness (High Octane's formula: red 0.3, green 1.25, blue 1.25 plus a little, of the brightest channel). This needs no VRAM, which tracks barely have outside the framebuffers. Every draw path (1P, split screen, clipped quads) carries the word unchanged. - The copies live in the level's memory pack, since the level renderer only takes texture data from there. They take about 600 bytes; the feature is skipped if the pack would keep less than 32 KB. They follow the original animation each frame (LevSuperTurboPads_Cycle). A face's low-detail texture covers the whole quad, so it turns cyan only when all four faces are pad.

Checking

tools/test-extras.c: the gradient's colours at each stage, that it never brightens again inside the window, the retail fallback for a driver with no room set, and the blue-fire rule.
Turbo Track with the all-super-turbo-pads cheat (CTR_DEV_CHEATS=1048576) and the autopilot, which hits the first pad at USF: Blue Fire turns the exhaust blue, the reserves meter draws, and the race trace is identical with every row on and off.
Cyan Super Pads: CTR_DEV_QUAD_DUMP after marking (palette words with 0x8000) lists the cyan faces. Hot Air Skyway has two super pads and ordinary ones, Oxide Station five super-pad quads, Cortex Castle two pad quads plus wooden tiles under super triggers that must stay unchanged, Turbo Track 30 pads, all super.
The gradient and the kept fire need a player: the autopilot doesn't powerslide.