Accessibility

Settings that let more people play your game. Each player has their own, applied at once and saved for them; you choose the defaults.

Setting	What it does
UI scale (0.5-3)	Every top-level UI element (a UI node whose parent isn’t UI) grows around the corner, edge or centre of the screen it’s nearest to: a health bar in the top-left corner grows from that corner, a button at the bottom right grows up and left, a centred menu grows from its centre. Clicks land where things are drawn.
Colour filter	Protanopia (red), Deuteranopia (green) or Tritanopia (blue): the picture is corrected on its way to the screen so colours that would look alike are told apart (daltonization). Strength 0-1. Simulate shows how it looks with the deficiency instead - for testing.
Subtitles (default on)	Spoken lines on the subtitle track.
Sound captions (default off)	Sounds’ captions on the subtitle track: “[door creaks]”.
Subtitle size, backdrop	Text size (0.5-3) and the box behind it (opacity).
Screen shake (0-2)	Scales every camera shake and trauma - 0 turns it off (motion sensitivity).
Controls	Rebinding: see input_rebinding.md and the Controls Menu template.

For players: an options menu

Add a UI Container (vertical) to your options screen, New Script, pick Accessibility Menu. It builds a row per setting - sliders, check boxes and a button that cycles the colour filter - applies each change at once and saves when the menu goes away (or with its Save button). Reset to defaults puts back yours.

Your defaults

Project Settings > Project > Accessibility: what every player starts with (saved in project.json as "accessibility"; only what differs from the engine’s). Players’ own settings are saved in accessibility.json next to their save files and loaded when the game starts.

Previewing colour vision in the editor

View > Colour Vision: Protanopia / Deuteranopia / Tritanopia shows the viewport as players with that deficiency see it (simulated). Use it to check that important things - team colours, health / danger, puzzle pieces - don’t rely on red vs green alone. Choose it again to turn it off.

Subtitles

The subtitle track shows lines at the bottom centre over everything (up to three; the oldest gives way), each for a time.

From dialogue. A Dialogue node’s Mode: Box (the dialogue box) or Subtitles - its lines go on the track instead, each for its voice’s length (else its reading time: 0.8 s + 15 characters a second), then the next follows by itself; the advance action skips. Lines can name a voice:

local vo = Scene.find_node("Cutscene")   -- a Dialogue node, Mode: Subtitles
vo:dialogue_show({
    { speaker = "Ada", text = "The storm's coming.", voice = "audio/vo/ada_01.wav" },
    { speaker = "Rex", text = "Then we run.",        voice = "audio/vo/rex_01.wav" },
})
vo:connect("finished", function() Scene.change_scene("scenes/level2.scene.json") end)

In Box mode the voice plays too. With the player’s subtitles off, the lines still play and time out (events too) - just unseen.

Captions on sounds. A Sound or Music node’s Caption shows when it plays, for players with captions on: [explosion], [footsteps behind you], [tense music].

From scripts.

Subtitles.show("Over here!", { speaker = "Ada" })                -- spoken
Subtitles.show("[alarm blaring]", { caption = true, duration = 4 })  -- a caption
local id = Subtitles.show("...")
Subtitles.hide(id)
Subtitles.clear()
if Subtitles.count() == 0 then self:next_bark() end

Scripting the settings

Accessibility.get("ui_scale")                 -- 1
Accessibility.set("colorblind", "deuteranopia")
Accessibility.set("screen_shake", 0)
for k, v in pairs(Accessibility.get_all()) do print(k, v) end
Accessibility.save()                          -- for the player
Accessibility.reset()                         -- your defaults (save to keep)

Keys: ui_scale, colorblind (“none”, “protanopia”, “deuteranopia”, “tritanopia”), colorblind_strength, colorblind_simulate, subtitles, captions, subtitle_scale, subtitle_background, screen_shake.

Tutorial: an accessible options screen

1. Make an Options scene with a UI Container (vertical, 440 wide) in the middle; add the Accessibility Menu script.
2. Open it from your pause menu: Scene.change_scene("scenes/options.scene.json").
3. Give important sounds captions (Sound node > Caption).
4. Put cutscene voice-over in a Dialogue node with Mode Subtitles.
5. Check your levels with View > Colour Vision.

How it works / performance

• UI scale applies a transform when each UI node draws (no extra render pass) and converts the mouse into that element’s space when it handles input (UI_GetMousePos) - widgets keep their own coordinates.
• Colour filter: one fragment shader on the final frame as it is drawn to the window (after post effects); free when off. The same maths runs on the CPU in Colorblind_Apply (tests).
• Subtitles are drawn after the scene’s layers in the game window (Play and exported games); they count down in real time, so a paused game keeps their pace.
• Screen shake is scaled where the camera builds its view, so the basic camera’s shakes and the advanced camera’s trauma both follow it.

Limits

• UI scale doesn’t move elements apart: a large scale can make elements near each other in the middle of the screen overlap - lay menus out in containers.
• An open dropdown list follows its dropdown’s scale; clicks on it from elements of another top-level UI group aren’t converted.
• The editor’s Simulate doesn’t draw the subtitle track (Play does).