Insult your friends in this silly local co-op game. Not a lot of game here but it's free and more importantly it's fun.

A 1st person shooter set in WWII, kind of. Many a crazy weapon or hat is to be earned with a lively community and a fair business model. A classic.

A 3rd person shooter where you play as a cyborg space ninja. Shoot and slash your way through enemies alone or in co-op. An all round good time.

A multiplayer shooter that puts the woo in John Woo. Let free your dramatic doves and jump through enemy fire in one of the best source mods on steam.

A turn based fighting simulator? A great time of flailing around attempting to punch other epileptics. Get some friends and start a little fight club.

A co-op topdown shooter that pays homage to the Alien film. Good fun with friends even if it is a little short.

An action rpg made for people who hated vanilla Diablo 3. The upgrade tree is insane and the gameplay is well executed. A must play if ever there was.

A quick arcadey action platformer that never ceases to be difficult. A solid time waster.

The best MOBA around and every hero is free. You can buy cosmetics but they don't effect the balance of the game. Be prepared for high levels of salt.

A solid twin stick shooter/action game that's entirely free and open source. The art, music, and overall style is delightful and it plays great.