http://www.zenimax.com/external.php?locale=en-us&url=http://stabyourself.net/mari0/
Quoting from the website....
A complete from scratch recreation of Super Mario Bros. with a focus on perfectly imitating the feel the 1985 classic gave us. Then give Mario a portal gun, add puzzle game mechanics from Portal and there you go. And if that wasn't crazy enough, play 4-player coop, with everyone having their own Portal gun!
Features
Features
- Complete recreation of SMB
- Elements from Portal
- Portal gun that shoots portals
- 4-player simultaneous coop
- Level Editor that was used to create the levels in the game
- 33 different hats
- Downloadable Mappacks
- Game modifiers for extra fun