This.
Is.
RET2GO.
Sonic RET2GO has actually been in the works for quite a while. I'm aiming to keep it simple, since this is the first hack of mine I'm showing.
The story is that Eggman has decided to return to Westside Island and hunt out the Chaos Emeralds to power a mind-control engine of sorts. Sonic and Tails, ever the alert heroes, hear about this heinous scheme, and so decide to stop the deviled egg's plan.
Onyx Glade Zone (Formerly Emerald Hill)
New layouts, new object placements, new rings, new palette
SymbioColony Zone (Formerly Chemical Plant)
New layouts, new object placements, new rings, new palette
Everything else
New title background palette, different stats each for Sonic and Tails, you now keep rings until you continue
Remember, screenshots will very likely indicate works in progress.