Play Tetris in Mac's Terminal app:

Here's how to do it.

First, open a new Terminal.app (/Applications/Utilities) window and type "emacs," then hit enter.

After the screen loads, press "escape," then "x."

Type "tetris" (lower-case) and hit enter.

There you have it, a fully playable game of Tetris. Use the arrow keys to control the blocks.