Tetrisphere is amazing, exciting, exilierating, and has got to be the most unique game even concived by man.
I'd better explain the game's concept. Brace yourself.
In the main game mode, you are face a sphere that has the classic tetris shapes all around it (like the squares and the t-shaped lines). All of these pieces, which consist of four minor blocks, cover the surface of the ball. Obivously, you can't fit perfectly squared shapes around a sphere. The developers found a way around that. Now, I can't explain it because there is a lot of math involved, but there are a few websites that figured it out. The sites are reletively easy too find. Anyway, you need to clear the ball of all these Tetris pieces, which consist of layers on the sphere. In order to do that, you get this thing called a 'shadow', which is an outline of a piece that you can destroy. For example, say you have a shadow piece in the shape of a square. What you need to do is find a square-shaped piece and destroy it (which is done by hitting 'A'). Now, there are several other things you can do with this square. You can hold it, (press 'B'), and move it around the sphere. When you quit holding the piece, it will explode. The idea of moving is to move Tetris pieces of the same shape together to set all of them off together and score more points. This is called a 'chain-reaction'. As you can imagine, the idea of this game is to rack up the points as effeciently as you can. Anyway, the goal of the main mode is to clear the sphere of all the Tetris pieces and clear a space on the main sphere. You see, there is a smaller sphere that has all the pieces stacked upon it. The pieces usually consist of 5 or more layers. Here is the challenge: you only have so much time to destroy a piece. If you exceed this time, or try to destroy a piece that dosen't match your shadow, you lose a life. And you only have three lives. The time is usually set for about 60 seconds on the easier levels. In order to push back the time, you need to destroy a piece, which will set the clock back about 5 seconds (on easy, that is). Whenever you exceed the clock, or push it against it's limits, you get magic, which is basically items that allow you to do certain things, like blow out huge chunks of the pieces.
To top it off, you have these robots that you choose to play as. They all have various attributes, but none have to much of a drastic effect on the game. They are good for matching certain play styles. Like to cruse around the sphere at high or low speeds? Find the bot you need and play away.
Along with the main game mode, which has a hundred levels, each with increasing difficulty, there are dozens of altered game modes you can play from, all offering unique challenges. Plus, the multiplayer is insanly fun, too. With all the chaos that happens on screen at once, it is a great surprise that the framerate never drops.
Which brings me to another point: the graphics. Despite being and eleven year old game, the graphics are not that bad, and the framerate never seems to drop, which is an enormous feat on an N64.
Another amazing aspect of this game is the soundtract. Composed by some guy whose name I can't remember (he did the Sonic Rush music, which he won an award for. Tell you what, look this game up on Wikipedia. I believe the composer is mentioned), the techno, big-beat style of musicis both unique, awesome, good to dance to, and perfect for the fast-paced style of the game. The tracts all have a unique style to them, and no two tracts sound the exact same.
So, that pretty much explains why this game is so amazing, so awesome, so... oh, words can't describe it. It simply needs to be played. So play it. From the insane gameplay, to the music, to the multiplayer, to the.... Oh, there's no need to describe it. It is so good you shouldn't need to read reviews about it. Go buy it. Play it. Have fun.
By the way, this was the first game I ever played, and I love it like nothing else. I wish I didn't sell it when I was little and didn't understand the concept of something going away and you never seeing it again. Well, I am a different person now, and I can honestly say I regret it. Damn me.