Is there a more satisfying experience in video gaming than clearing four lines at once in Tetris? (A move technically referred to as a tetris.) It turns out there is: watching an AI developed by Greg Cannon play Tetris flawlessly while prioritising clearing four lines as frequently as possible.
Like human players, Cannon’s impressive StackRabbit AI gets better at playing Tetris through repeatedly playing and analysing the game to develop improved strategies. But unlike human players, StackRabbit has nerves of steel and doesn’t start to panic as the ever-growing stack of tetrominoes approaches the top of the play board, which it pairs with lightning-quick reflexes to play one of the most mesmerising and impressive rounds of Tetris you’ve probably ever seen.
Clearing four lines at once is not only satisfying, it’s also the best way to quickly rack up points when playing Tetris. But while, theoretically, a talented player could stack tetrominoes indefinitely, the 8-bit NES version of the game (which is used for The Classic Tetris World Championships) starts to melt down as gameplay approaches level 29 where the game’s speed doubles. The developers assumed this was the point where human players wouldn’t be able to keep up, and while some have managed to make it just past level 29, the game starts to quickly exhibit graphical glitches as the load on the NES’s processor increases.
Human players have managed to hit NES Tetris high scores of over 1.6 million points, but with artificial human limits removed, Cannon’s StackRabbit AI managed to reach level 237 of the game with a score of 102,252,920 points after around an hour and five minutes of gameplay. Watching the AI’s unbelievable run is often as confusing as it is mesmerising as in later levels the game starts using the wrong graphical elements to build the tetromino pieces.
The glitches don’t phase the AI, however, which works by pre-planning for whatever random piece appears next. It prioritises clearing four lines at a time, but due to the randomness of the falling pieces, and the occasional scarcity of straight tetrominoes needed to complete a four-line tetris, the AI does occasionally have to clear single lines, and once in a while ends up with a gap in the stack of pieces, but watching it quickly recover is equally amazing.