Prospero

Prospero was one of Valve's first game designs, slated to come out shortly after Half-Life. The game emphasized exploration, an intricate storyline, and combat via "psionic" powers. The protagonist of Prospero (known as "the librarian" or "Aleph") underwent a series of design changes during the early development of the game. One iteration relied heavily on the use of psionic amplifiers to augment her innate abilities.

As the design of Quiver started to take over some of Prosperos initial goals, Prospero became a massive multiplayer game. Prospero was also intended to be distributed, with a mix of Valve and usercreated worlds that can be accessed through an in-game library, and each game would be running on it's own server. Online distribution, server browser, a friend finder, user-created worlds and other ambitions initially developed was eventually to become Half-Life, Steam, and Valve's huge modification support.