- PNG support would be nice
- collision detection
- jumping and crouching
- octrees
- light and shadows
- shooting
- network support with a chat
- material (like walls, discs, water + swimming)
- weapons, lamps, healthpacks etc.
- computer-controlled opponents
- joystick support
- sound support
- clean up the code
- a screenshot function
- better video mode code
- rain, snow