Tetriz

Tetriz is a Tetris clone, written in Oberon language with the aims of being small (6 kB) and running in a window. The game is controlled via the numerical keypad and comes in three variations: Tetriz, MegaTetriz and MiniTetriz. The plain version has the same width as most Tetris variants, whereas MegaTetriz runs in a roughly 2½ times wider window. MiniTetriz is only four blocks wide, giving a new dimension to gameplay.

Tetriz was later adapted to run in a text window, under the title of Contris, which also saw use as a BBS door.