Before diving into specific hacks, it is important to understand why Sonic CD is such a prime candidate for modification.

Many fans prefer hacking the more flexible Genesis engine to recreate Sonic CD's aesthetic: Sonic Megamix

: A technically impressive project that attempts to port the entirety of Sonic CD back to the standard Sega Genesis/Mega Drive hardware. The Sonic Hacking Contest (SHC) The most complete experience / top hacks?

The original Sonic CD has a notoriously easy final boss. This hack extends Collision Chaos and Quartz Quadrant, then adds a brand new "Final Zone" level. Using left-over data from the Sega CD development disc, this hack rebuilds a scrapped level called "Metallic Madness X." You fight a prototype Eggman mech that never made the final cut.