One bullet (0) - I could see some interesting story based games here, yet as a mechanic it seems cluky. Most of all I don't want to test 200 games later on that have to do with firing and retrieving bullets all the time.
One minute (-1) - much too generic and limiting at the same time. There can be fun games within this theme, but again: testing would be very annoying.
Dying planet (+1) - only a setting, so not really that great, but I like it :P
Ancient world(+1) - same as above.
Two points of view (+1) - This actually gives many possibilities for both narrative and mechanic design.
Fragile(+1) - very non-descriptive. I still gave it a plus because it immediately gave me a bunch of ideas I really like.
It's spreading (0) - there are so many games with this theme already and most of them are just so stressful.
Inconvenient super powers (-1) - Themes like this come up every time. I don't doubt that good games within this theme are possible, but it's jsut to limiting and will result in clunky games.
Start with nothing (-1) - so basically any progression game ever?
Running out of space (0) - don't like it, but technically a decent theme. Not very original thought.
Nothing is explained (+1) - mechanically this is already the case with most jam entries, so I was about to give it a (0), however if people really take to it as a theme, the resulting games might actually have better learning-concepts without overtly stating rules or having a tutorial?
If you don't see it, it doesn't exist (0) - Could result in many similar games. But solid theme.
Color as a gameplay feature (-1) - too many games have done this recently.
One enemy only (0) - sure why not.
Build a dungeon (0) - too specific, but why not.
Control two things at once (-1) - forcing games to be clunky in a gamejam that will already result in many clunky games is just not a good idea.

So yea, quite a few cop-out reasons by me. But no 42 puns made it to round 1, so I'm kinda happy.