I would think size isn't as important as content. Ie just say that 500K is the max size, so that modem and broadband cant easily try it out vie JWS.
Then make 3 or so major catagories so you can get a spectrum of people.
- Graphics Flare (Just gimmicky stuff to visually impress)
- Complete game (Covers tic tac toe to full 3d everything)
- Neato and Useful (Something between a game and a demo. Examples would be - a Sticky Note program, where the backgrounds are animated. An app which shows you how to fold an Origami bird. )
If they absolutely have to been only games then -
- 3D (Using 3d engine to produce a 2d game doesn't count here)
- 2D Scroller (top down types, sideways spaceship types, etc)
- 2D Non-Scroller (checkers, pac-man, etc)
Judge them on -
- Creativity (3)
- Judge's Personal Slant (2)
- Audio (present or not) (1)
- Code comments (If people are going to learn, they will need these) (2)
- Did it meet the size limit (1, -5 if it went over)
- 1 Person team (2 for a one person team 0 for a two person)
- Directions provided and accurate (1) You need to know how to play
Adding the points up gives a max of 12 points. 5 of those depend on a person, so that might be enough to differentiate entries.
My thoughts any ways.