Stick around for a bonus teaser at the end!
From the video description:
Mordheim: City of the Damned, Rogue Factor's turn-based tactical-RPG adaptation of Games Workshop's tabletop game Mordheim set in the Warhammer world, is about to enter Early Access imminently! To celebrate this occasion, take a look at the new official website of the game, as well as the first gameplay video of Mordheim: City of the Damned, explaining some of the mechanics you'll enjoy throughout the Early Access and beyond!
If you're interested in Early Access, head to the game's official site.
The free DLC expansion that's "MMO simulation so good you'll think it's real" will be released on Steam on November 20, 2014. In an effort to perfectly simulate an MMO, the expansion includes five classes: warrior, rouge(?), magician, hunter, and microwave(???).