Tetris for the original Game Boy is still one of the games I play daily, and for good reason.
The object is to make lines with the shapes in a continuous fashion until the game ends, or you lose. It isn't all easy when you reach the higher speeds, called levels, and include a handicap for yourself with the B-options on the menu. The handicap places a set number of random blocks on the screen when you start, making it hard to form lines at first, but eventually clear out and you have a normal game. If you get a high enough score in each of the game modes, you can see rockets being launched. That's the only reward you get in the game, but it is very satisfying to achieve.
Most people have heard the Tetris theme at least once in their lives, and if you haven't shame on you. It is one of the catchiest themes in video gaming. Even though it is 8-bit, you won't hear a Tetris theme that gets any better. Also, the sound effects of Tetris are some of the most classic. The sounds you get when you score four lines at a time, a tetris, is the best sound you want to hear during a hectic level nine game.
Overall, Tetris for the Game Boy is one of the greatest puzzlers to hit gamers ever. If you at least have a Game Boy Advance, you need to search for this game.