What is the name of the computer game where you can paintball shoot burn etc your computer default background

I don't remember the name, but it used to be at www.gemtree.com.
Edit: I looked it up on there, it is now INCLUDED with the Peter program. I'm not sure if you can get a standalone, I'll look for you. Edit #2: Found an old version online for you :)
http://download.freewarefiles.com/files/weapon_closet.zip