Atmosphir (released in October 2004 for private beta) was a 3D adventure game for Mac, PC and barely Linux. It was based entirely on user-created levels and games.
Atmosphir was primarily a 3D design tool, allowing designers to do many things. Players were also able to create their own unique character, with a selection of hairstyles and clothes, as well as weapons, and more purchasable items from the Market, and play other users' games.
After what is often assumed to be a financial/funding issue with Minor Studios' Atmosphir, the offices shut down the games servers and website in 2011. Some of the old developers (Minor Studios) formed a team (BlackPony) and worked on a new game called Voxelus. Although the game never reached pre-alpha, it was a way of keeping in touch with the community. After its shaky future was noted, a thread entitled "Community Preservation" was made on the Voxelus forums, linking users to a new forum by the name of OneMoreBlock. This is also reminiscent of the way that the community was originally introduced to Voxelus, with Adz making an exception to the rules by posting a thread advertising Voxelus on the Atmosphir forums.