Monday Night Combat!

Team Fortress 2 (TF2) is the sequel to the game that put class-based, multiplayer team warfare on the map. One of the most popular online action games of all time, TF2 delivers constant free updates including new game modes, maps, equipment and, most importantly, hats.

Zandronum is a multiplayer oriented port, based off Skulltag, for Doom and Doom II by id Software.

Aion is a visually stunning MMORPG where your character wields devastating powers and sweeping wings to explore a celestial world.

Alien Swarm is a free top-down shoot-em-up video game by Valve Corporation. It is a remake of the Alien Swarm mod for Unreal Tournament 2004, and it was developed by the original team, which was hired by Valve during the course of the development process.

A game imitating the look of DOTA, now with a dedicated server and ratings saved in your history to make matches equally fighting for both parts.

Alien Arena is a free and opensource first-person shooter game that combines a 1950s-era sci-fi atmosphere with gameplay similar to Quake (series) , Doom (Series) and Unreal Tournament (series) . Alien Arena focuses mainly on online multiplayer action, although it does contain single-player matches against bots.

Tremulous is a free, open source game that blends a team based FPS with elements of an RTS. Players can choose from 2 unique races, aliens and humans. Players on both teams are able to build working structures in-game like an RTS. These structures provide many functions, the most important being spawning. The designated builders must ensure there are spawn structures or other players will not be able to rejoin the game after death. Other structures provide automated base defense (to some degree), healing functions and much more... »

Warframe situates players as members of the Tenno race, newly awoken after years of cryo-sleep into a solar system at war. Reborn into a corrupt era, the Tenno are sought by the oppressive Grineer Empire for annihilation. Warframe armor is the key to overthrowing the Grineer by providing players with unique offensive and defensive powers to explore, upgrade and master during purpose-driven radical raids.