I had a couple of time to think about ideas what I could do with the theme “Evolution“. Somehow one idea got stuck in my head and I couldn’t find another idea and before my head explodes, I’ll just stick with the idea!
My idea is to make a platformer (yeah I know ANOTHER platformer like the 1000 other ones but it works best for my idea) where you play a creature and every time you die, you will play the level again as a new evolution of your previous form. HOW you evolve depends on how you died. So for example if you fall into your death, on the next respawn you can jump higher, or get a double jump, or even wings. If you get killed by fire/lava, next time you have a thicker skin that lets you endure fira/lava better.
That means that every time you die you get more powerfull, but in return the more evolved you are the less points you get. The challenge is to beat the game with as less evolutions as possible. I still haven’t thought about every detail but I can think about it once I actually got something playable 
I’m still not sure what my main creature will be, first I thought a dinosaur, because dinosaurs are awesome, but I think a lot of people might do something with them. On my way home today when I thought about the game I saw a squirrel running from one side of the street to the other and I thought a squirrel might work as a main creature
I’ll use XNA with C# for programming.
For graphics I’ll use PyxelEdit and maybe combine it with Tiled to make the maps.
I still have no idea what to use for the music (or if I even have the time to make music). I’ll use bfxr for the sound effects.
I started programming and as I advanced in developement I changed my whole concept every 20 minutes as I discovered more “innovative” ways to do something.
At the end of the competition I just got a bunch of user friendly APIs glued together and a game that lastet 13 seconds. Just focus on creating the game you thought of at the beginning(you really should do so), and don’t make the same mistake like me.
Viel Glück!