Emberwatch

A 3D horde-survival game ("bullet heaven") built with Flutter and flutter_scene. You hold a moonlit forest clearing against a spider swarm until dawn. Weapons fire on their own; you move, collect embers, and pick upgrades.

Play it in the browser (needs WebGL2; checked in desktop Chrome).

Run

Requires Flutter 3.47 stable or newer. Flutter GPU is already enabled in the macOS, iOS and Android runner files; the web build needs nothing extra.

flutter run -d macos --profile
flutter run -d chrome --profile
flutter run -d <phone or simulator>
flutter test

Platform	Checked on	Result
macOS	Apple Silicon, profile	120 fps five minutes into a run; 82 MB release app
Web, JavaScript	headless Chrome (WebGL2), release	60 fps with 275 enemies on screen
Web, WebAssembly	headless Chrome (WebGL2), release	60 fps with the patched engine; about 43 fps with 0.24.3
iOS	iPhone 17 Pro simulator, debug	60 fps
Android	Pixel 9 Pro emulator, profile	Renders correctly over OpenGL ES

The Android emulator here rasterises on the CPU, so its frame rate says nothing; no physical phone has run the game yet. Debug builds run at full speed too.

With the published flutter_scene 0.24.3, the WebAssembly build is the slower of the two: its WebGL backend copies instance data a byte at a time under dart2wasm. The live site is built against a patched engine (bdero/flutter_scene#533), which makes it the faster build (about 4.5 ms of frame work against 6.7 ms for JavaScript). To reproduce it, point dependency_overrides at that branch.

Controls

Action	Keyboard	Touch	Gamepad
Move	WASD / arrows	On-screen stick	Left stick / D-pad
Pick an upgrade	1, 2, 3 or click	Tap	X, A, B (left, middle, right)
Pause	Esc / P	Pause button	Start
Start, restart, resume	Enter / Space	Tap	A

Gamepad input has unit tests but has not been tried with a controller.

Phones are locked to landscape. The run pauses when the app loses focus.

Quality

The title screen cycles three tiers and toggles sound; both are saved, along with the best time. Phones start on medium (low on the web), desktops on high (medium on the web).

Tier	Changes
High	2048 px shadows in three cascades with soft edges, ground-truth ambient occlusion, film grain, god rays
Medium	1024 px shadows in two cascades, cheaper ambient occlusion, 80% of the swarm
Low	No ambient occlusion or flashlight shadows, 40% of the ferns and branches, 55% of the swarm

Every tier lets the renderer lower its resolution to hold the frame rate.

How it is built

Path	Role
lib/game/game.dart	Owns the scene and the run: phases, leveling, the tick order
lib/game/world.dart	Ground, scattered props, obstacles, lighting and post-processing
lib/game/swarm.dart	Enemy simulation and instanced rendering with procedural leg IK
lib/game/arsenal.dart	Weapons and passive upgrades
lib/game/director.dart	Spawn pacing across the ten-minute night
lib/game/fx.dart	Sprites, transient lights, lightning, ground decals
lib/game/embers.dart	Experience pickups
lib/game/sfx.dart	Sound effects and ambience
lib/ui/hud*.dart	HUD and menus, as ordinary Flutter widgets over the 3D view
lib/gamepad.dart	Controller input

Every spider is drawn through four instanced meshes (body, eyes, upper legs, lower legs), and its eight legs are posed each frame by two-bone IK on an alternating gait. Nothing about the enemies comes from a model file.

Tools

Every asset is generated by a script in tool/; nothing is downloaded. The generators run in headless Blender (5.2) and are deterministic.

• blender -b -P tool/gen_surfaces.py -- . renders the tiling forest-floor and bark textures and computes the night-sky environment map.
• blender -b -P tool/gen_props.py -- . builds and bakes the rocks, boulder, stumps, logs, branches and ferns in assets/models.
• blender -b -P tool/gen_trooper.py -- . builds the player character, its rig and its Idle, Run and RunBack clips.
• blender -b -P tool/gen_icon.py -- . draws the app icon and writes every size for each platform.
• tool/synth_audio.py generates every sound in assets/audio.
• tool/deploy_web.sh [remote] builds the WebAssembly web app and publishes it to the gh-pages branch.
• tool/shoot.sh <dir> <seconds,...> [ENV=value ...] builds, runs and saves frames. AUTOPLAY=1 drives a bot, SKIP_TO=<seconds> jumps into the night, QUALITY=low|medium|high picks a tier, CAM_ZOOM, DISARM=1 and FORCE=title|levelUp|dead set up a shot.

The same options work outside release builds on every platform: as URL query parameters on the web (?AUTOPLAY=1&SKIP_TO=120), or compiled in with --dart-define=DEBUG_OPTIONS=AUTOPLAY=1,SKIP_TO=120 for phones (a release build honours only the compiled-in form). A scripted run logs its frame rate every two seconds.

Status

A complete, playable ten-minute run, not a finished product. Known gaps:

• No physical phone has run it, so the low and medium tiers are unmeasured on real mobile GPUs.
• Gamepad input is unit-tested but untried with a controller.
• Balance and the sound mix have had no human playtest.
• The bundle id dev.scratch.emberwatch is a placeholder and no signing is configured.

License

MIT, for the code and for every generated asset in assets/.