In a way, this Quake mod laid the groundwork for future generations of game-related artificial intelligence, whether opponent-based or active non-player characters. Created by Steve Polge, the Reaper Bot allowed Quake gamers to play in a multiplayer environment without the need for other human players. This was especially handy when Internet gaming was relatively new and connections weren't exactly stable. Before facing elite gamers, players could practice each map with numerous bots, fine-tune those twitch-based skills, and learn the camp spots.
What made this mod so cool was that the AI opponents seemed rather smart...too smart for that matter. Other bot-based mods used pre-generated waypoints that felt more track-based than anything natural. However, the Reaper bot navigated the maps on its own (dynamic mapping), learned on the go, and could even function and perform like a human by opening doors, tracking and attacking players, avoiding ledges, etc. The damn things were challenging, to say the least, taking no prisoners as if long-time, champion players (Thresh) were pulling the strings.
After Reaper, Steve Polge was hired by Epic Games to work on the AI for Unreal--he even supplied the multiplayer bots. The Reaper was discontinued, but the mod saw various third-party improvements, such as skin packs and other small features.