I can still remember the first time I played through Super Metroid. I never did get a chance to play the original Metroid, but Super Metroid was a consuming experience. You could easily get lost in the giant maze, and the limited direction of the game made exploring a great amount of fun.
However, it was primarily a side-scrolling type game, and I didn't expect much when it translated into 3D on the next-generation systems in Metroid Prime. However, I did hear good things about the newer versions, but had never gotten around to playing them. So I decided to pick up a used copy for $5, and boy, has it been worth it!
While it took a little bit to get used to the first-person-shooter type display (or DOOM appearance, as my wife noted); once I got into the game it felt like the same indulging experience. While I have yet to finish the game, I have to admit that it's about as much fun as I've had playing a single-player game in a while. So if you've got a GameCube, $5, and some time to kill, I strongly recommend grabbing a copy of this game if you haven't already.
Heck, I'm already looking forward to getting my hands on the sequel, Metroid Prime 2: Echoes. But I guess I've got to get through the one I've got first.