Don't get me wrong, this game kinda blows. It's level design is the exact opposite you'd want for a classic Sonic game, the time-travel mechanics are stapled on-top at best, and the special stages, oh the special stages. (And the versions before the '11 Taxman remaster were the essence of jank)

But this was the game as a kid I spent hours mastering to a T. I learned all of the level layouts, where all the item monitors, sign posts, and robot generators were, and the fastest route through all of the above. I still may not be that great at the special stages (even though I 1-cycled Special Stage 2 once), so I get the good ending the hard way.
The soundtracks to both versions are a delight to listen to over and over. Believe in Yourself was my anthem for a while. Sonic Boom still makes me cry a little.

This stupid blue rat means so much to me, and it's my dedication to this game that solidified it.