Orion: Prelude is a first-person shooter and online cooperative multiplayer game developed and published by Spiral Game Studios for Microsoft Windows. In the game armed players work together to defend generators against dinosaurs. The game was conceived in 1998 by developer David Prassel and was originally launched as a Half-Life 2 mod known as Orion: Source. Prassel formed Spiral in 2010 and announced plans to release the mod as a full game to be known as Orion: Prelude. The game was eventually launched as Orion: Dino Beatdown in 2012 although it contained numerous glitches and was poorly received. In 2013 Spiral replaced it with a sequel known as Orion: Dino Horde although players and media outlets viewed it as a minor update to the original game rather than a successor. In 2014 it was updated again and rebranded back to Orion: Prelude.