I'm building a TDS(Top Down Shooter) Studio/Engine that allows users to make their own TDS and save it as an exe for other people to play.
If any of you have any ideas then please tell me and I'll add them in.
It has collision detection as well for the bullets and the player; the walls can be moved around by the user dragging them with the mouse.

I've got some screenies of it at the moment:
The basic system:


Firing a bullet:


After the bullet hits an explosion and some debris is created:


Hiding like a wimp:


8-Directional movement and shooting:


Adding a wall in:


And here's the wall: