Valve's latest featured fan campaign for the PC version of Left 4 Dead 2 should be instantly familiar to anyone who's enjoyed the developer's seminal Half-Life series. The five-chapter campaign is set on the streets of Half-Life 2's police-state metropolis, City 17, where the oppressed citizens have been replaced by zombies, and the totalitarian Combine have been replaced by zombies, and ... yeah, just about everyone's been replaced by zombies there.

As with all its featured community levels, Valve's temporarily hosting servers running the City 17 campaign. If you feel up for a romp through your ol' crowbaring grounds, you should take advantage of this delightful opportunity.