They made a VERY IMPORTANT change to Sonic 2 on this Sonic Origins compilation. In the original, after getting all the Chaos Emeralds, Sonic has the ability to turn into Super Sonic once he collects 50 rings. Sorry, that might be a spoiler. Super Sonic moves even faster, jumps higher, and is invincible (except for being crushed or falling off the bottom of the screen), but as his rings count down as you use him, you have to constantly collect rings or he’ll run out and you’ll turn back into Normal Boring Sonic with no rings, and invariably die.
Which is fine, except that as Super Sonic, platforming is far trickier as the physics change and he’s much more slippery and quick. So really, you want to be saving your rings until you get to a hard bit or a boss, then triggering The Change. You couldn’t do that, though, as the game decided that the way to trigger The Change was to jump. Yes, just jump. Which, in a platformer, is tricky to avoid doing. UNTIL NOW! Yes, in Sonic 2 in Sonic Origins, you can turn into Super Sonic at will! You still jump, now you also have to press another button in the air. A game changer. No more franticly trying to race to the end of the level before your rings run out, or having to make jumps over pits of doom even more difficult because Sonic acts more like a mouse pointer than a physics-adhering creature. Amazing.
Oh, and the game? Completed it mate. With all the emeralds. That Tails is a git though, especially on the Special Stages.