pub fn sim_tick(state: &mut GameState, geom: &SimGeometry)Expand description
Run the platform-agnostic body of one sim tick: state updates + ambient
spawn helpers. Save scheduling and demo-driver autopilot are the
caller’s concern (they live in app.rs::sim_loop on native).
When geom.powerups_paused is set (a full-screen modal is open), the
powerup engine is skipped entirely — no spawns, no lifetime ticks, no
cooldown advancement. The base tick still runs so auto-FPS, modifiers,
achievements, and HUD count-ups keep flowing.