I’ve never done this before and my idea for a game is still pretty vague. I’ll post more details as I go along…

For now I’m going to be using:

Java

with libGDX for graphics and input etc. http://code.google.com/p/libgdx/

jbox2d as the physics engine (maybe) http://www.jbox2d.org/

gimp and blender for making graphics and so on.

Good luck!