Blockout is a puzzle videogame, created in 1989 by Polish developer - California Dreams, designed by Aleksander Ustaszewski and Mirosław Zabłocki. The game is the logical extension of Tetris into the third dimension. In Tetris, the player manipulates a set of tetrominoes which fall into a two-dimensional pit (seen from the side). The aim is to solve a real-time packing problem by forming complete rows, which then disappear and score points. Poor play leads to incomplete rows, caused by inefficient arrangements of tiles; these rows do not disappear, giving the player progressively less space and less time to play subsequent pieces.

Similarly, in Blockout, the player manipulates a set of polycubes which fall into a three-dimensional pit (seen from above; the pieces appear in the foreground and fall away). The pieces can be rotated around all three axes, and moved horizontally and vertically. The aim is to form complete layers.