Video:
http://www.youtube.com/watch?v=RY39fWwI ... re=related
http://www.youtube.com/watch?v=1WPLKFI_ ... re=related
http://www.youtube.com/watch?v=1bdhQRuVhkk
Images:
http://sauerbraten.sourceforge.net/screenshots.html
img1
img2
I've also made a video for it, and this also demonstrtaes it's modability:http://www.youtube.com/watch?v=9WznkLkPwkU
Pretty sweet huh? Even crap computers can run it pretty fast.
Linkage
EDIT: Forgot to say it's an FPS. Sorry. Still, I would take a look. Pretty fun to mess around with the editor. Which leads me to the fact that oneline is also great, and has an online editor, for collaborative efforts.