4D Miner is a 4-dimensional survival sandbox game that allows players to explore an infinite, randomly-generated, 4-dimensional world.
It bears some resemblance to other first-person sandbox games, but its in-game worlds are not simply made up of 3D cubes. 4D Miner's worlds have four spatial dimensions, and as a result, they are primarily made up of 4-dimensional hypercubes.
The real universe has only three spatial dimensions, but a universe with four spatial dimensions can be simulated by computers. Since humans can only directly experience three spatial dimensions at a time, the game allows the player to explore and interact with a 3-dimensional slice of its 4-dimensional world.
The defining feature of 4D Miner is that the player can rotate their 3D slice of the world by scrolling with the mouse wheel. This means that in theory, the entirety of the game's 4-dimensional world can be explored.