Cool article. Check out this video http://www.garrysmod.com/?dont_buff_my_pylon=60&SpartanIV_Compilation_Movie
I messed around with Garry's Mod back in the day but I have no idea how people create these things...

"It'd be nice to see more games based on creating rather than destroying." Seeing things like that video, and remembering how awesome Rollercoaster Tycoon was, makes me agree with this so much.