From Hard Drop - Tetris Wiki
Tetris for Electronica 60, the original creation which Alexey Pajitnov programmed in Pascal on an Electronica 60 computer, features black and white graphics, with a pair of brackets representing each block in a tetromino. A player controls input through the number pad and carets/vertical lines outlining the playfield.
 See also
- Tetris The Grand Master 3 Terror-Instinct, where the bracket-based representation of the blocks are given tribute to in (pieces turn into brackets after the player reaches Level 1000 in Shirase mode)