Tetris has been done to death, so I doubt this is anything new.

There must must be a "language" one could define to compute using Tetris.

• shape has a starting rotation defined
• rotated i * TAU/4 radians (i is int)
• also has the two reflections (flip vert, flip horiz)
• colors are meaningless (?)
• no "user input": drop them as you intend them to land
• (for example) the columns are bits
• rows collapse as in the game.
• input can be shape + rotation + reflections + horizontal_translation, in sequence, assuming no conflict with existing shapes

You can do computations. If you called the bottom row "output" and some other row(s) as input, you could do arithmetic. somehhow....!