I would just like to inform that under LD 27 I encountered a bug with collision, I could not get it to work. So after 2 hours I asked in the Ludum dare IRC if I could search for information about it and someone replied that I could do any type of research. I knew a good source about collision and I used that information in the game, here is the video:

It’s from The Cherno, for those who don’t know who he is.

He is a great java game programming teacher on youtube.

Here is his Ludum dare entry:

http://www.ludumdare.com/compo/ludum-dare-27/?action=preview&uid=14133