Valve wants some extra help with refining Team Fortress 2. They announced that they'll be holding open beta testing for the multiplayer shooter.
Beta testers will be guinea pigs for a variety of upcoming changes. You'll test the tuning of classes, items, and weapons as well as map changes. Larger experiments (for example, doubling player health) and new technologies will also be previewed. Here's a list of changes being tested in the initial beta:
Three Natascha variants:
-25% damage, -25% health
Spin-up/down time increased, slowdown-on-hit effect falls off over distance.
cp_granary: new entrance added into the RED and BLU mid ramp room.
cp_5gorge: 5 CP version of cp_gorge.
Misc balance changes:
Players being healed by a medic are immune to movement-impairing effects generated by hit-scan weapons.
Testing and tuning various class, item, and weapon changes
Testing map changes and variants
Running higher level, game-wide experiments (like doubling player health)
Testing new technologies without the risk of breaking the game
Anyone who owns a copy of TF2 can participate in the testing. Simply select "Team Fortress 2 Beta" from your Games list in Steam to download and install.