As Evan mentioned last night , Rising Storm is currently undergoing a free Steam weekend. But if Tripwire's brutal FPS doesn't appeal, there's another, far less harrowing route to moneyless multiplayer murder. Size Five Games' enjoyable one-on-one arcade battler Gun Monkeys can be trialled for free from now until this Sunday.
Gun Monkeys is a manic two-player deathmatch set inside procedurally generated arenas. Your job is to: a) collect power cubes, b) bring those cubes back to your power core, c) kill. Mostly kill, to be honest.
In addition to being free this weekend, the game can be purchased for 50% off at £2/$3. That price secures two copies of the game, which was one of a couple of methods Size Five's Dan Marshall employed to get people into its dwindling servers. The other: the game will send you a free Steam key if you find yourself in an empty server for a few minutes.
Here's a trailer, featuring The Actor Kevin Eldon: