The powerball.0.2.beta.zip file you have requested: Modifications / Powerball / Powerball 0.2 Mod - 14.23mb is not available. Perhaps try browsing all files for the game Wolfenstein: Enemy Territory and upload any files you want to share or are missing. This is the only information we could locate:
You compete for the domination of one single ball in the middle of the map, the objective is to score it in the enemy goal but at the same time protect your own goal from the enemy team. Powerball is a small modification for Enemy Territory.