Think Minecraft, with different worlds, data packs, and multiplayer; but instead of a Survival mode, it's built from the ground up to be customised, like a game engine of its own.
Building Blocks is a canvas, doing the heavy-lifting of physics, rendering and networking, so you can focus on programming mechanics. Groups of resources and behaviours can be bundled in "data packs," so you can reuse content created by the community. With Building Blocks, you can make mini-games, adventure or puzzle maps, or even a world for an RPG campaign!
Little has been revealed about this projects as of this time, because it's in early design stages, but here is a screenshot.
