Sonic 2. My little brother and me played it so much that we could get Super Sonic during Act 2 of Emerald Hill. When we first started, it took us until like Aquatic Ruins to get all of the emeralds. Honestly, I played the Sonic 1 and 2 mod a week ago and still have some of the Special Stage ring patterns memorized. I was calling them out in my head before they came.