I remember inputting cheat codes in the music test for Super Sonic anytime in Sonic 2 , but I remember there was either a way or a cheat code to get “Hyper Sonic”. Does anyone remember?
From the (now defunct) cheats.freeola.com:
Run forward in Oil Ocean, Act 2 until reaching the green jet springs. Jump on the very last spring and hold Right. Sonic will hit a group of spikes before becoming stuck in the side of the wall. Jump out to transform into Hyper Sonic. In this mode, Sonic can run faster and jump farther than Super Sonic, but is not invincible.
Here is a YouTube video showing the glitch: