Sorry to self-promote, but, Angeldust (https://angeldu.st https://angeldu.st) is a single, persistent, real-time voxel world going for about eight years now. Ca

Sorry to self-promote, but, Angeldust (https://angeldu.st https://angeldu.st) is a single, persistent, real-time voxel world going for about eight years now. Can handle 300+K players on a single server due to massive parallelism. Unfortunately we don't get those player numbers right now, but hopefully in the future!