Todo:

 - Checkpoints
 - Time
 - Score
 - Different levels.
 - Menu
 - Better collisions
 - Better bullets (vertex array).
 - Lod heightmap
 - Lod trees etc...
 - Shaders and HDR.
 - HUD messages, know who killed who etc.
 - Radar of some kind
 - AI ships.
 - Different ship models, different classes of ship.
 - Buildings and various structures
 - Dynamic content loading (and unloading).
 - Axis aligned (or limited) sprites for trails.
 - Altitude limit.
 - Clouds? / weather / night and day.
 - Detailed terrain (only when near camera).


For LOD and dynamic content:
 - Ability to free memory and resources when not needed
 - Draw with a specific lod value. Multiple models with different poly counts etc. May even be sprites at very large distances.
 - Grass, lots of sprites close up but drop number with distance.