The other offer going on this weekend is Rock of Ages for just $2.49 (75% off).
The Killing Floor: Halloween Hillbilly Horror Event is also ongoing and you can pickup the game for $4.99 on it’s own or for $9.99 with all the DLC included.
Weekend deals End Monday at 10am PST (1pm EST). All prices on Steam are in USD and exclude tax. All games are digital downloads and require installation of the Steam client.