QUB3D is a machine that can be found all round the island. There is one in first strip club as you go in the front door on the left. There is also one in the same bar as the first pool hall you enter. (See "Pool Shark") The high score is 10,950, but the achievement will not unlock until after you finish the game. The main point of QUB3D is that blocks will fall from the top to the bottom much like Tetris, and you need to get similar colors to land so that 4 blocks of the same color are connected, and then that color block will disappear.
**Can be done after completing story mode**