Tetris break is intended to help you stay motivated to continue doing / finish your anki cards. A tetris-like game will show up after you review a certain number of cards, and it will have you clear a line before you move on.
You can configure some settings, including the number of cards you need to review before you can play and a custom background image that will be revealed as you fill up the board. The addon settings screen can be accessed via Tools -> Add-ons -> Tetris Break (double click).
