I love themes like: - Gardening - Reflection - Towers

They are single words, I like them because they give you freedom to be creative and create so many games from them. For theme "gardening" for example, you could make a tower defense game with gardening mechanics, mini farming simulator or a platformer where different platforms grow from the plants. The point is that it gives you creative freedom.

But themes like: - "Not as it seems" - "find the exit"

Are immensely vague and it takes time to even decipher how to make a game idea from it that follows the theme. I hate those kind of themes. Plus I hate themes that are of the format: "Running out of __"

Anyways, just sharing couple of opinions.