WBtris

WBtris is a Tetris clone that runs in a window on the Workbench. Hence, it is fully system friendly, and runs even on systems with graphics cards. Since it predates AGA machines and AmigaOS 3.0, it only supports the standard four system colours, using dithering to achieve a sufficiently wide range of colours for its blocks. It has a high score function, selectable start level and statistics over dropped blocks.

As of version 1.54, you may design your own blocks apart from the standard Tetris assortment, by defining them in a plain text file.

Written in DICE C, WBtris is open source cardware.