The Terasology project was born from a Minecraft-inspired tech demo and is becoming a stable platform for various types of gameplay settings in a voxel world. The creators and maintainers are a diverse mix of software developers, designers, game testers, graphic artists, and musicians.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Well written in Java
Java is well documented.
Pro Nice looking
Shaders, bloom, film grain and other effects can be enabled.
Pro Free sandbox alternative
The game is inspired by other titles like Minecraft and Dwarf Fortress.
Pro Fully moddable
In the game you can create a mod and submit it as a module. You can select multiple modules when you make a new world.
Pro Extremely modular
The engine allows mix-and-match of features that you need.
Pro Active community
The community is very active in the development of the game, they participate regularly to Google Summer of Code and Google Code In.
Pro Can be Minecraft competitor
An open source alternative, fully customizable; easy mod support based on module pieces.