This Super Mario deathmatch Unreal Tournament III mod turns Unreal into side-scrolling deathmatch goodness! You will need the UT2D mod installed first (download link below). The UT2D mod will turn Unreal Tournament III into a 2D game and the UT2D-SuperMario_Beta (created by FrontAXL) is the Super Mario Bros level.

Required files to play this on PC or PS3:
UT2D - http://utforums.epicgames.com/showthread.php?t=610415

UT2D Super Mario mod is available for download on PC and PS3.
PC: UT2D Super Mario Unreal Tournament Mod for PC
PS3: UT2D Super Mario Unreal Tournament Mod for PS3

Super Mario UT2D mod screenshots: