Duck Game, Adult-Swims multiplayer action game was released last June, and will be free to play from now until 8PM UK/1PM PT on May 1. You can also pick it up at a 40 percent discount from now until May 2. You can check out its trailer below.
The other free weekend game is the exuberantly-titled Ghost in the Shell: Stand Alone Complex – First Assault Online. This first person shooter was first released on Early Access last December, and is still currently in development. It expects to launch officially later this year as a free-to-play title. You can check out the gameplay trailer below (via. Machinima).
The game will also be available to play from now until Sunday at 8PM UK/1PM PT. The game is also available to buy, with a sale price of £1.99/$2.49 running from now until May 3.