Can't say I'm too keen on the restricted theme either. With the previous competition in mind and the number of participants, I'd say we need a theme that is as open as possible.

With that said, I think that pretty much cancels the 'same engine' idea as well, as we will be giving people an advantage if they already know the engine.

The fact that people can choose their own basis, can't really be considered an advantage. Remember we want to see games, not half done demos. If an entrant decides to write a new engine just for the competition its his choice, but he should also realise that he will loose valuable time. Every hour spent on a engine, means an hour lost for the game.

Abstract sounds cool. It needs some creative thinking for a game concept. I think I'm up for that though...