Portal: Survive! is a live-action short film based on the Portal game, and its tie-in comic Portal 2: Lab Rat.
Portal: No Escape
Check out this excellent short film based on the Portal video games, called Portal: No Escape.
Valve have created Expiration Date, a 15 minute animated short featuring all the Team Fortress characters.
Team Fortress 2 - ZombiU Crossover (Source Filmmaker)
This Team Fortress fan animation created with Source Filmmaker is a cool tribute to the ZombiU CG trailer.