So, I'm curious about this. Been playing Sonic 3 for years. Sonic 3 & Knuckles is probably my favorite Sonic game of all time. I've never noticed any physics differences that are stated in the rules. Are there any examples? I took to Google, but it just wants to show me Sonic 4 stuff. o.o;

So a few examples:

• S3: Have to be at a complete stop to start spindashing, S3K: can be moving slowly to start spindashing
• S3: Slopes give you some momentum, so can't do the above, S3K: all fine.
• S3: If Insta-Shield's effect is active when landing, it will be counted towards the next jump, so you can't insta-shield in quick succession, S3K: fixed so the insta-shield is reset when landing.
• S3: Going upside down in Carnival night means the walls have no collision, S3K: walls have collision when upside down.
• S3: Knuckles' areas are incomplete so certain skips and tricks that are used in S3K (e.g. Launch Base) don't work.
• S3: Act 2 stationary capsules exist beyond the boss before the boss has been defeated, so can potentially complete HC2, CN2, and IC2 without hitting the boss. S3K: capsules only exist after defeating the boss.

Dude. Neat! I never knew. Thanks for the info! :)