I've seen the video of rolli robot. He's got some good mobiltiy and potential. What I imagine is one with the same mobility but with the ability to shoot pinkpong balls and battle other robots. The rolli robot would be able to roll to any area and then pop open and shoot the balls at a target of its choice. Little sensors could be stuck to the robots involved in the battle to determine target points, which could then be used to determine the rules and winner of the battle.
By Lord Duck
Other robots from Synthiam community

R2D2's Robot Navigator
This is my new pocket robot: Navigator. Constructed from aluminum, cut with scissors, and assembled with rivets. Powered...

Zxen's Robomannequin
This is Eve. What do you guys think so far?

Elvisexmachina's 3D Printer Quadruped
I am slowly designing and printing an 8 servo quadruped. I will integrate parts like the sensor and the camera after I...