Why do I think this? Well, let's see. The graphics? It doesn't need good graphics for little block shapes. The gameplay? Fun and addicting, and eventually reaches the perfect level of challenge. The plot? A puzzle game doesn't need a plot. The music? Very good for Gameboy standards, and Type A is an old Russian folk song called Korobeiniki.
Now, that's only small stuff when you think about THIS. You know that great gameplay I was talking about? It's ****ING ENDLESS. No, it's literally endless. The game is portable, so you have an endless, portable game with fun challenge and extremely catchy music. If batteries didn't have a lifespan, you could play this game endlessly until the very day you die. And, it also has limitless replay value. Don't you find that amazing?
So yes, when you really look into it like that, Tetris is the perfect game.
Note: This is all opinion based. Please realize that.