Team Fortress 2 is the game that keeps giving. Valve's class-based multiplayer hit has received a steady stream of updates since being released nearly five years ago. Last year, the game became free to play for anyone with a Steam account. Tomorrow, it gets a new cooperative gameplay mode dubbed Mann vs. Machine. Check out the official trailer:
Up to six players will be able to take on The Gray Horde, a robot army whose soldiers bear more than a passing resemblance to TF2's characters. In addition to mowing down those enemies, players will have to stop bomb-carrying robots and contend with sentry busters, which look like kamikaze mines with legs. The most interesting element could be the giant-sized robots teased at the end of the video and described briefly on the Mann vs. Machine site.
Valve has also added a new map, Mannworks, and it looks like there are plans for even more content in the co-op realm. In case you're wondering how this all fits into the greater Team Fortress 2 universe, there are a couple of comics that help set the stage.
Commenters will no doubt chime in that Valve should concentrating on finishing Episode 3 instead of expanding TF2, but those things aren't mutually exclusive. Maybe we'll get a sense of what's coming on the Half-Life front at Gamescom later this week. Thanks to Rock, Paper, Shotgun for the tip.