Kumoon is a 3D puzzle game that has you playing a chick with a gun. Chick, as in baby chicken. You shoot boxes, which react in a semi-realistic physics-simulated fashion. Once a level is solved (given that this is more proof-of-concept than anything, this is pretty easy) you can use unlimited ammo to blow up everything on screen and watch it all react with each other. Oh, and all the stuff you shoot stays on screen, without vanishing, up to an arbitrary number of objects that you can change.
Other levels can be made using text files with individual box coordinates, or names of typical box structures, such as pyramids or walls.
Jailbreak, the game Henke refers to above, can be found with a Google search for the terms "Jailbreak," "Stephen Roantree" (its author), and "Deliberate Games." The game can, as far as I can tell, only be found at a certain well-meaning and valuable site that hosts older games of ambiguous copyright status, though Jailbreak itself is totally free and legal for distribution. It is, if you will, a kind of rest HOME for games that might be construed as UNDER the radar of the DOGS of the gaming industry. (I understand your anality, TheOutrider, but I hope you alerted Henke of your edit, since it removes just about any possibility of the average user finding the game if they are interested in it.)