Well, this is certainly ... unexpected. Telltale Games recently uploaded a brief teaser trailer (posted below) for an unannounced title featuring a few cryptic messages, as well as the line-up seen above. Fans of adventure games (and, uh, team-based shooters) will recognize the silhouettes pictured therein as Tycho from Penny Arcade Adventures, Max from Sam and Max, the Heavy from Team Fortress 2 and Strong Bad from Strong Bad's Cool Game for Attractive People. That's in order from left to right, in case you're really unfamiliar with the aforementioned games.
We could spend the rest of the fantasizing about the manner in which these four properties could be blended, but we won't have to wait long for the actual explanation -- the trailer promises more info on the untitled project will be released next Thursday, September 2.