Murder Ball
This was a kind of 'Tag' game, played by hurling a tennis ball at someone's head from shockingly short range to make them 'it'.
As throws from behind were perfectly legal, it was quite possible not to realise you were playing until you felt a stunning blow to your occipital.
It was soon decided that tennis balls simply weren't murderous enough, and so they were replaced firstly by cricket balls, which themselves were succeded (on account of not having 'enough corners') by large cubes of solid pine stolen from the woodwork room.
Luckily, the game was outlawed before someone took the decision that lumps of timber simply weren't 'Ninja throwing star-y enough'.
written by An*y Man*h, approved by Susan

The climax of Murder Ball - for the loser - was often the 'Tunnel of Death'. Everyone playing would stand facing a wall, with their arms forming the roof of the tunnel. The loser would then have to crawl through while everyone kicked the shit out of him, while somberly intoning 'Tunnel of Death, Tunnel of Death, Tunnel of Death'.
No-one ever died in the Tunnel of Death. Some wished they had.
written by St* Ch*iney, approved by Conor

We played a variant called "Roller Balloon", due to a very tenuous similarity to Rollerball.

Basically, you all sit in a circle and pat a balloon to each other. The person who allows the balloon to touch the floor gets the shit kicked out of them by everyone else. This game is interesting more for its combination of the frankly rather gay activity of patting a balloon with ultra-butch macho hitting.

Can also be played with a kinder egg.
written by excluded pupil, approved by Matt