Aetherius is a voxel based game experiment being written in Java with LWJGL. It provides a procedural universe that runs infinitely in every direction across infinite worlds, with thousands of materials. All the non-procedural content is made with a suite of software that ships as part of the game. Aside from the pre-baked content and the modder, the game also procedurally generates content from mixing and matching an abundance of components that the player has the ability to add to or remove from. This content includes NPCs, Quests, Machinery and Materials. Aetherius is a true sandbox. The player can toggle every single aspect of vanilla gameplay, and construct their own game rules to suit themselves. It is fast approaching a viable alpha test phase.
I threw out the crappy old world generation system I had, and implemented an AI algorithm from DungeonWars to seek and generate only ever the nearest empty chunk. This image demonstrates a cheater's view, I walked one way, then teleported a long distance away to show the rough sphere shape that the world generates in (most apparent beneath the world in the image)