Yes, the men are made out of Balls. No, not what you were thinking.
Basically a Half-Life 2 mod, but there's awesome wall walking, and a dedicated server so we can all play.
Courses designed for Wallalking
Ball people.
And lots of Cool weapons.
It's also Free and 41 megabytes. Go download it. It is fun. More than you would think from just wall walking.
EDIT: and you can Triple Jump and there are crazy awesome powerups.