>>714067182 (OP)Sega's ego, it was like a furry version of 3D Realms' during DNF's development. They had to make the BIGGEST game ever with TONS of gameplay variety to show off what the Dreamcast could do, which is why half of Sonic Adventure fucking sucks.
You'll notice that besides a few hiccups that Sonic's gameplay in Adventure plays good, great even in some cases. It has some of the same nonlinear elements of the classics with higher paths and shortcuts. The movement is mostly responsive and Sonic is fast without compromising control. SA1 actually aged very well if we're only looking at the character in the title.
But then it has Tails, who should have just got his own levels because his flight makes everything turbo baby mode easy, there's Amy who actually controls like shit and moves slow, and Big, just, everything about Big. I think Knux and Gamma played okay, but that's a problem in itself, they were just okay, mostly because again, they just reused Sonic's levels. There's a reason they cut most of this stuff for SA2.
Sega had too many idea people at Sonic Team and throwing everything at the wall to see what sticks clearly never worked even when they accidentally made a game, or part of a game, that was pretty good.