Prospero is a cancelled PC game that was in development by Valve while they were working on Half Life / Quiver. Initially the game was meant to be an action adventure, with an “science fantasy epic” storyline, lots of exploration and a complex combat system with psionic powers, but after a while the project became a MMORPG in which Valve wanted to let users to create their own worlds to have an ever-expanding universe. Prospero was canned in 1997 when Valve decided to move their effort to Half Life. Key features that were planned for Prospero were later integrated in other Valve projects, as Steam and Portal 2.
As we can read on Half Life Wikia:
In the Half-Life sound files folder (Steam version), the music files commonly known as “Dimensionless Deepness”, “Steam in the Pipes”, “Threatening (Short)”, “Traveling Through Limbo” and “Vague Voices” are named “prospero01” to “prospero05”, which could imply that the tracks were initially made for Prospero.
Thanks to an interview with Marc Laidlaw by François Aymes for Jeuxvideo.com, we can read some more details on the project:
The Prospero development was halted in 1998, was it because of Half-Life ?
It was halted because some of us went to game shows and saw things that looked like Prospero, and felt that we weren’t doing anything that was going to make us stand out in the crowd. The project was flailing, struggling for identity, and there wasn’t a sense of great confidence. It was a natural thing to move more of our attention to Half-Life. Prospero was dead in the water well before Half-Life 2 came along.
Was Prospero supposed to feature a single player adventure ? Can you give us an idea of the plot ?
It straddled the line between single player and MMO, which was not something we could have pulled off back then. There were all sorts of possible plots, but we never got far enough to have to decide which one would work for what we were building.
Thanks to Valve Time we are able to know more about this interesting project, check the video below!