Solomon W. Golomb's Polyominoes

Origins
A polyomino is a plane geometric figure formed by joining one or more equal squares edge to edge. It is a polyform whose cells are squares. It may be regarded as a finite subset of the regular square tiling with a connected interior.

The name and item, polyomino, was invented by Solomon W. Golomb in 1953. The tiles were the inspiration for the game Tetris, invented by Alexey Leonidovich Pajitnov, released to the public on June 6, 1984.

The Tetris effect (also known as Tetris Syndrome) occurs when people devote sufficient time and attention to an activity that it begins to overshadow their thoughts, mental images, and dreams. People who play Tetris for a prolonged amount of time may then find themselves thinking about ways different shapes in the real world can fit together, such as the boxes on a supermarket shelf or the buildings on a street. In this sense, the Tetris effect is a form of habit. They might also dream about falling Tetris shapes when drifting off to sleep or see images of falling Tetris shapes at the edges of their visual fields or when they close their eyes. In this sense, the Tetris effect is a form of hypnagogic imagery.

Easy spin refers to the property of a Tetrimino to stop falling for a moment after left or right movement or rotation, effectively allowing someone to suspend the Tetrimino while thinking on where to place it.