And so begins the 30 Days of Gaming Challenge...
I'm pretty sure that my first game was the classic Sonic the Hedgehog 2. I spent hours on this game, and completed it several times over the years. It never gets old for me, and still has several paths I've never explored. It was the first game I had bought a strategy guide for too, though I don't think I ever used it much except for the cheat codes. Level select was a beautiful thing in a game where you can't save.
I've played all of the early Sonic games - and I think it was the 2nd which had the level design down the smoothest. Each was inventive and fun (though Hill Top Zone was a bit dull), and the music was fantastic. I present Metropolis Zone and Mystic Cave Zone for your consideration here:
The real innovation and genius came with the release of Sonic and Knuckles. Combining it with Sonic and Knuckles to play through the game as Knuckles was a really fun thing to be able to do, and allowed you to find even more paths to explore. As far as I'm aware, no other game lets you plug one into the other to mix them up like that. Epic.
An eternal legend, and I love it dearly.