Of the virtual worlds for less-known blockchain games, Cryptovoxels is one of the smallest, though also the only one that will keep on growing! If you want to learn more about these types of games, head over here.
If you're interested in exploring a virtual world, "CryptoVoxels" is one of the fastest to start in. You can enter by following a URL click, it doesn't require any fancy software or immersive hardware. In-world building is done by simple shapes that snap together like Lego blocks.