In addition to Arkane Studios' hit game Dishonored being available for free on Xbox Live for Xbox 360 until the end of the month, it is also available for free play on Steam all weekend. Borderlands 2 is also available during the weekend as a free play game.
The first-person stealth action game is playable for free until Sunday at 1pm Pacific Time (4pm Eastern Time). During that same period, you can buy the game for 75 percent off its regular price. The regular version will cost you $5, while the Game of the Year version is $10.19.
You can find the game on Steam. It is rated "M" for "Mature" by the ESRB.