Timmy the MadfoxA SEGA Game Gear, playing a Master System cartridge?
What sorcery is this?
With the Gear Master from Beeslui, it's actually possible!
Anisse@Madfox_Timmy Did you know?
There is a Game Gear cartridge of Castle of Illusion; except the game runs in Master System mode (i.e. just like with the SMS cartridge adapter, with the Game Gear doing the resolution scaling), to simplify the port.
There are small differences though: https://www.smspower.org/forums/19127-ComparingTheSMSAndGGVersionsOfCastleOfIllusion
And this is why a Game Gear emulator must also be able to emulate the SMS. Or at least run a the scaled version of Master System game, also called "SMS mode".
The differences are minimal though, since the Game Gear is basically a portable Master System, but with a smaller screen resolution, more colors and stereo support. Some Master System versions do have a different sound chip though, to allow richer sound.