How can do some thing like that Sonic 1 gba remake by stealth?
 

How can I something like he did. I remember reading something that had said he used specific utilities to convert the game from genesis to gba but, I wanted know what kind of software he used and if it was widely available and if it would be possible to do something like that with sonic 2 or 3. I know this is a very old topic but it intrigued me to the point I needed to find out how to do it.

https://info.sonicretro.org/Stealth

https://duckduckgo.com/?q=Sonic+1+gb...ffcm&ia=videos

So he used C and converted the code from the Sega genesis version to GBA. Thanks for sending me those links they were helpful.

Glad to help.

Glad I came across this thread. Would bookmark those links as well.