Team Fortress 2 - Man vs Machine is getting his first major update and is of course completely free. It adds two new tours, new loot and has a improved matchmaking system.

New Tours

There are two new Tours of Duty to MvM mode, in addition to Operation Steel Trap (hard), they've added Operation Oil Spill (less hard) and Operation Gear Grinder (very hard).

New Loot

Together with the new tours they've brought some tour-specific loot that you can only get from Operation Oil Spill or Operation Gear Grinder. Rusty, blood-covered 'bot heads for the intermediate-level Operation Oil Spill, and some 24-carat diamond 'bot heads for the expert-level Operation Gear Grinder.

Improved Matchmaking

They now made it so you can select multiple missions you'd like to play, to maximize the chances of finding compatible players as quickly as possible. Also they added some handy buttons that'll let you select all missions of a particular difficulty level, or all missions not yet marked off on a Tour of Duty. And when your MvM group beat a mission, they've now made it so that when you beat a mission to death in Boca Raton or elsewhere, you and the other players on the server are sent back to the matchmaking screen as a group, so you can keep playing together.