When it comes to suggesting themes, I hope you guys consider these nuggets of, err, not necessarily wisdom, but... Something.

Bad theme considerations:

• A game mechanic is not a good theme (e.g. "jumping")

• A genre is not a good theme (e.g. "first person shooter")

• A graphics style is not a good theme (e.g. "pixel art")

• A super broad thing is not a good theme (e.g. "universe")

• A limitation may be a good theme, but not always

Good theme considerations:

• Good theme is open to interpretation (e.g. "up or down?")

• Good theme does not limit game genres ("racing" is more limiting than "speed")

• Good theme does not limit cultural genres ("anime" or "cyberpunk" would do so)

• Good theme applies to all kinds of graphics styles, or even other media like tabletops

• Good theme may reveal itself after the jam is done as we see how people interpreted it :)