Around the year 2000, when I was roughly 5 years old, I had access to a Genesis emulator with a bunch of ROMs. It had a somewhat weird mix of Sonic games, as Sonic 1 didn't work and Sonic 2 was missing, but luckily Sonic 3 and Sonic & Knuckles worked fine, and I quickly got addicted to those. Other games included Sonic 3D Blast, Sonic Spinball and even Sonic Crackers.
The first Sonic game I actually legally owned was either SADX on PC, or Sonic Heroes on Gamecube. From there I played basically every Sonic game that was available on PC, Gamecube, Xbox or GBA, and stopped right before Sonic '06. Since then, the only Sonic game I've played in full is Sonic Mania...