I can never understand this, but a lot of people are impressed that the Sega Genesis could make more parallax layers than the Super Nintendo, but I always thought the complete opposite.
Some of the games I have like Super Mario Allstars, and Donkey Kong Country have levels with 3 parallax layers, that look completely natural and real. But the first time I played Sonic 2 or Thunder Force 4, I was like, wait there is something completely wrong with the parallax? It doesn't scroll up or down? I can see horrizontal lines in the middle of clouds where layers end? It looked all wrong. Then I noticed that there is ever only up to two real layers onscreen, where as I always knew the Super Nintendo could naturally do 3, it looked like the Genesis was limited to 2.
Most people argue that games like Sonic 3 and Thunder Force 4 have more layers than the Super Nintendo could have, but I really don't care for that kind of parrallax. It hurts my eyes sometimes looking at the fake parallax scrolling and it doesn't look anything like parallax should look like.