Minecraft - A block-building game that allows you to create and explore entire worlds from scratch.
Roblox - Reimagining the way people come together.
Minetest - Minetest is a near-infinite-world block sandbox game and a game engine, inspired by InfiniMiner...
LEGO Worlds - LEGO's Minecraft competitor
Terasology - Terasology (started under the name Blockmania) is an open source project started by Benjamin...
Infiniminer - Infiniminer is a multiplayer block mining game with several different player classes to choose from.