One of the most famous hacks, it combines Sonic 1 and Sonic 2 into one massive game. It allows you to play as a team (Sonic, Tails, and Knuckles) and includes the ability to collect Super Emeralds to reach Hyper forms.
Even with the hack installed, you typically have to earn the transformation: Super Sonic & Hyper Sonic in Sonic 1
A "Hyper Sonic in Sonic 2" ROM hack is a modified version of the original game file that introduces the and the Hyper transformation.
Most hacks include Hyper Sonic’s signature double-jump ability, which triggers a screen-wide flash that destroys all nearby enemies.
Unlike the yellow Super Sonic, Hyper Sonic features a rapidly cycling color palette (rainbow effect) and after-images (ghosting) when moving at high speeds.
Use a tool like Lunar IPS to apply the hack file to an original, unmodified Sonic the Hedgehog 2 ROM.