Sonic 2, Sonic 3 and Knuckles. Only reason I don't say Sonic 1 is because Labyrinth always kicked my ass at the end while Sonic 2 and Sonic 3 and knuckles I kept going till I mastered it. Grew up with these games because my parents played them, and as I kept playing I progressively got better and better to the point that I'd be Tails and be guiding my father or mother through the levels verbally as I tried to kill the badniks around for them. great memories with that game, like finally figuring out that damn barrel when even my parents didn't know what the trick was, or accidentally finding a way to bypass the chemical plant rising pink water section completely. Still play these games via emulator on my computer, in fact just did my little tradition to beat 1-3(four if you count knuckles separate) last month for the first time this year.
Speaking of which We Are Legion it's quite simple, you just need MotioninJoy tbh