The first time you power up as Super Sonic. Made all those annoying special stages worthwhile...
Tails returns from being shot out of the sky in incredibly short order with a freaking rocket booster attached to the Tornado, powerful enough for the little biplane to run down Eggman's space shuttle. Gadgeteer Genius indeed.
How about Tails' Big Damn Heroes moment at the end of the game when you don't have all the Chaos Emeralds; he actually saves Sonic's life by catching him with the Tornado as Sonic falls from space back down to Earth, saving the Hedgehog from falling to his death.
Except if you're playing as Tails, in which case Sonic does so.
Knuckles has easy access to places in various levels that Sonic has trouble accessing. Every Checkpoint, every hidden extra life, every alternate path (Chemical Plant is probably the best), it all proves that even after twenty-plus years and who-knows-how-many extensive playthroughs, the level design still has some tricks up its sleeve.
Twenty-one years after its release, Christian Whitehead, known to the Sonic fan community as "Taxman", helped spearhead a remastered version of this game for the iOS and Android systems. Tails and Knuckles have their full abilities (as seen in Sonic 3 & Knuckles ). Knuckles obeys the same rules with regards towards rings as Sonic and Tails (requiring the same amount of rings in the Special Stages and losing his rings upon entering/exiting a Special Stage). You get the extra life for reaching 300 (but not 400, 500, 600, 700, 800, or higher) rings unlike in the original that only gave you extra lives for 100 and 200 rings. (Though this fact only really comes into play during Casino Night Zone. As a matter of fact, Emerald Hill Zone Act 1 is probably the only other time a player can realistically hit the 200 ring mark consistently.) The Special Stages have a new HD isometric view point and 2P VS Mode has double the amount of levels to race around in, plus an extra character. But how does he really make it better? Three Words: Hidden. Palace. Zone.
And to think with all that, this quality game was still considered rushed out of the door, and as a result had to scrap a few things. Here's what is known to have been scrapped so far:
The Time-Travel gimmick of Sonic CD
Enough levels to create another game.
18 different enemies
Unused sprites for enemies that made it into the final game