Steam now offers early access to TUG, a "multiplayer, open-world, sandbox-RPG using social sciences to allow players to impact how the game evolves." They will be adding features (and raising the price) as time goes on, and here's an outline of where the Early Access alpha currently stands:

The game currently features two gameplay modes: Creative Mode and Survival Games. In Creative Mode, players can unleash their creativity on the landscape of TUG by digging and building the terrain and exploring the near-infinite procedurally generated world. In the Survival Games, players spawn on a multiplayer map and must race to collect resources, craft weapons and tools, and battle it out to the last Seed standing. Players must utilize the environment to forge tools and weapons, create traps, and sabotage opponents.

Currently in alpha testing, the game will have new features and gameplay systems continuously being added, upgraded, and expanded on. New modding tools will be released periodically so players can create their own maps, tools, and weapons and share them.