Portal: Survive! is a live-action short film based on the Portal game, and its tie-in comic Portal 2: Lab Rat.
Portal 2 - Perpetual Testing Initiative
Valve are introducing the Perpetual Testing Initiative for Portal 2 with this new amusing trailer.
Team Fortress 2 - Mann vs. Machine
A robot faction is introduced into the Team Fortress 2 equation, via this amazing new trailer by Valve.