When you first launched Minetest, didn't you think it was just Minecraft? Actually not. Although their interface, style, and gameplay are almost the same, Minetest is essentially a free, open-source and cross-platform voxel game engine (written in C++ and Lua, using the Irrlicht Engine). It was created by Perttu Ahola and first released in 2010, and is now developed by a team of volunteers, with significant contributions from the community. It's available for Linux-based systems, FreeBSD, Windows, Mac, and Android platforms, and provides an API for users to create their own games and mods written in Lua.

L3DT (short for Large 3D Terrain) is a realistic and high-quality large 3D worlds (both terrain maps & textures) generator on Windows platform. It's specially designed for game developers and digital artists, developed by Aaron Torpy (the proprietor of Bundysoft) from Australia.

World Machine is a powerful and flexible 3D world terrain generator specially designed for game engines or 3D rendering software. It provides procedural terrain creation, simulations of nature, and interactive editing for you to produce realistic terrains with high-resolution heightfields, textures, and meshes.