This game never gets old and you can continue to play over and over again, vying to beat that high-score.
Tetris needs NO OTHER features. In itself, it's a great game. High scores are recorded, and even still, between friends, all you need to know who has the high score on your phone. Once you beat it, you can push it in their face, and let them try to beat your score. It can't really be that hard to remember one friend.
Overall, Tetris is easy to learn (if you've never played), highly addictive, and simply an amazing classic.