...WHO GIVES A SHIT!?
The system requirements to run Yoshi's Island are the same as the ones needed to run Home Alone: a cartridge with the game on it. It doesn't matter one bit to me if Nintendo "cheated" by adding a $2 chip to the game cart. It still runs on my SNES.
You fanboys are friggn ridiculous.
...to say that Yoshi's Island can't run on the only system it actually ran on (before the slightly inferior portable ones released a decade later) is...crazy. You guys are nuts.
Your hyper sensitivity to anything you consider critical of the SNES is getting the best of you again. Although you claim to not care about this stuff, you've once again resorted to yelling and swearing when it is suggested that competing consoles could approach what the SNES has done. At the same time you call people pointing out an indisputable technical fact "friggin ridiculous" "fanboys".
The SNES runs most SNES games at 2.66 MHz.
The Sega/Mega-CD CPU runs at 12.5 MHz (you made a big deal of this earlier).
The SFX2 chip runs Yoshi's Island at 21 MHz.
The extra hardware that Yoshi's Island requires to run on the SNES isn't something minimal like the mappers most NES games use or compression chip to increase cart space. It's a full on CPU. But it's not even a huge 150% speed increase like the Sega/Mega-CD... it's 8 times faster than what the SNES runs most games at.
Sure the Retrogen is just a tiny pass through strip that could fit inside a single cart along with a Genesis game PCB. But the SNES isn't really running the Genesis games and couldn't even if they were reformatted like a PCE CD to HuCard conversion.
12.5 MHz Sega-CD = "really damned powerful... The PCE is a much slower machine and the CDROM2 doesn't add anywhere near as much power to the PCE as the MCD does to the MD"
21 MHz SFX2 = "a $2 chip"
Back to the original point, there is nothing special about Yoshi's Island that distinguishes it from other SNES games in any way which would make it impossible to port to Sega Genesis. Except the extra hardware. That is why it is a poor example. Sure you could super charge the Genesis with a SFX2, but again that would remove the only thing unique that makes it more difficult to adapt to Genesis compared to regular SNES games.