A small retro vector-arcade game built on suit — the Scala Native + SDL3 + Cairo UI toolkit. The whole game is one suit canvas widget: a useFrame callback steps an immutable GameState each frame and the painter draws it as white line-work on a black field, the classic arcade look.

brew install --cask edadma/tap/asteroids

This installs Asteroids.app (in Launchpad / Applications) and a CLI asteroids command, pulling the runtime libraries (sdl3, cairo, freetype). Launch it from Launchpad/Spotlight, or run asteroids from a Terminal in your desktop session. The binary is unsigned, so the first launch needs a right-click → Open to get past Gatekeeper. (A GUI app only opens a window from the logged-in desktop session — running it over SSH or from a non-console shell won't show a window.)

sbt run

This compiles, links a native binary, and launches the window. To produce the standalone executable without running it:

sbt nativeLink
# -> target/scala-3.8.4/asteroids

Requires the Scala Native toolchain (Clang) plus SDL3, Cairo and FreeType, which suit links against transitively.

• Shoot rocks to score: large 20, medium 50, small 100. Large rocks split into two mediums, mediums into two smalls, smalls vanish.
• Clear every rock to advance a level — each level spawns more, faster rocks.
• You have 3 lives. A collision costs a life and respawns you at centre with a brief blinking invulnerability. Lose them all and it's game over.
• A flying saucer crosses the screen now and then and shoots at you: a big one (200) with sloppy aim, a small one (1000) that tracks you tightly and sharpens as your score climbs. Its shots break rocks too, and ramming it costs a life.
• The screen wraps: fly off one edge, reappear on the opposite one.

Every effect is synthesised at runtime — no audio files — and played through sdl3's core audio. The shot, the size-scaled explosions, the ship's thruster rumble, the saucer's continuous warble, and the level-clear chime are all generated as PCM on the fly. The warble follows the original cabinet's analog circuit (a continuously swept oscillator) rather than switching between fixed tones.

• Vec2.scala — toolkit-free 2D vector math; the simulation is pure arithmetic over it.
• Model.scala — GameState and the pure step function (ship, bullets, rocks, the saucer and its shots, collisions, wave/level progression). No toolkit types.
• Sound.scala — procedural audio: Synth generates each effect's PCM; Sound plays them through an sdl3 voice pool, with dedicated topped-up streams for the continuous thruster and saucer sounds.
• Main.scala — the suit app (Game.App), input handling, and Render, which draws the whole frame onto suit's Canvas (shapes via strokePath).