Light is key (0) - Meh. I like using light and there is still enough variety, still it seems oddly limiting and I don't think I would like most games based around this theme.
Evolve (+1) - Usually I wouldn't have given this a plus, but since there are so few themes I like, I guess I gave it a plus.
You start with everything and end with nothing (0) - hm. Sure it's a twist, it leaves enough space... but it's just not terribly exciting.
Four elements (-1) - overused.
Decay (+1) - originally gave this a 0, but actually quite like this.
Use the enemies to win (-1) - too specific. People keep suggesting similar things thought.
Duplication (0) - meh. Expanding environment (0) - meh.
Safe in the dark (+1) - Might actually be a tad too specific, but could be fun.
Tiny machines (+1) - Probably a really bad idea. And yet, I just like these ideas.
3 Rules (0) - Lots of possibilities. Could be mechanical (as in go) or narrative (as in asimovs laws of robotics), but otherwise a bit bland.
You can't control the player (-1) - Themes that make jam games more clunky are just not a good idea.
Alchemy & Magic (+1) - not very original, but I never got around to making a dedicated alchemy game and always wanted to. So yea selfish plus.
Four-colour palette (-1) - nope. almost the same as four elements, but more restrictive and in a way I dislike.
What you create you must destroy (0) - meh.
One of you is a traitor! (0) - Nice idea, sounds like werewolf or mafia, but most ideas are multiplayer based and thus it might not be the most suitable for everyone.