My personal Opinion

Sonic the Hedgehog 1 was an instant hit the blast processing in the Sega genesis make the game fast paced and the 16 bit Processor make the game look smooth and the animations fluid. The only problem was that the Special stage could cause headaches and nausea with the spinning and changing shapes. Sonic 2 evolved  what sonic 1 did making the special stage not spin and the background being the  color of the chaos emerald you were going to get. If you get the certain amount of ring the game ask you to get. The problem with this game was Miles "Tails" Prower. When he hit Robotnik (if your from America) or Eggman (if your Japaneses) He have Invincibility Frames and you fall through him and get hit.