Don't want to spend any cash? Steam thought of that. Both Orion: Dino Horde, a multiplayer shooter that pits man against dinosaur, and Call of Duty: Ghosts, a game that pits Riley the dog against helicopters, are free to play this weekend. Should you wish to buy after you try, Orion is available for $1 and Ghosts is reduced to $30.
Finally, Bohemia Interactive's military sandbox game Arma 3 is 40% off this weekend and available for $36. The game features a variety of single-player and multiplayer operations, and allows active personnel to edit certain gameplay scenarios and employ custom mods.