The game is the logical extension of Tetris into the third dimension. In regular 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.
The game allows the player to choose the set of blocks they will play with and the size of the pit. Pits range from 3x3x6 to 7x7x18, giving a total of 195 possible pit sizes (counting e.g. 3x5x6 and 5x3x6 as identical). Three block sets are available — flat, basic, and extended — making a total of 585 possible game modes.
Under "Main Menu", three of the possible 585 game configurations are recommended to the player. These are called "Flat Fun", "3D Mania", and "Out of Control", and use the flat, basic and extended block sets respectively. Other features of the game include:
Demo mode: This is not a pre-recorded game of an expert playing, but a well-programmed bot that plays a good game in any given setup. The bot finds smaller pits and more complex block sets more difficult and achieves correspondingly lower scores.
Practice mode: A game where the pieces do not move down with time. The player can manipulate the pieces for as long as they like before dropping them into place with the space bar. This is very useful for beginners learning to navigate the 6 keys required to rotate in two directions around each of three axes. Practice mode scores are not recorded in the High Scores file.
The Blockout Halls of Fame list the top ten scores ever in each one of the 585 permutations. Scores can be submitted to the site, and the high score database is updated about once a year. World rankings depend on a number of appearances in these tables and scores achieved, suitably corrected by "M-factor", which captures the varying difficulty of different game modes. A world championship is held each year in Germany, usually in Ingolstadt in November.
There is also a new real-time online high score database. Players can upload not only their high score, but also their entire game, and watch replays from others. This allows players to learn by watching the playing and stacking techniques of other gamers and to identify possible fake high scores.
Polycube block sets
The flat block set consists of polycubes that all fit into a single layer. These are effectively just two-dimensional polyominoes with thickness added, and include all but one of the members of the n-polyominoes up to n=4. (The tetromino consisting of four squares in a row is excluded.)
The basic block set consists of the seven polycubes present in a soma cube, all of which are polycubes of order three or four.
The extended block set consists of all n-polycubes up to n=5. This is a block set with 41 members, consisting of the single cube, two cubes together, the 2 tricubes, the 8 tetracubes, and the 29 pentacubes.
The New York Times reviewed the game in an article about educational software for mathematics, writing that Blockout "doesn't pretend to be educational, but the skills required to master it are not unrelated to mathematics, particularly geometry."
- L. R. Shannon: No-Frills Mathematics Instruction The New York Times, 23 January 1990
- NOSS, A. (1994): Förderung der Raumvorstellung bei 10- bis 14-Jährigen durch das Computerspiel BLOCKOUT. Diploma thesis, University of Vienna.
- Lesser, Hartley, Patricia, and Kirk (May 1992). "The Role of Computers". Dragon (181): 57–62.