Full list of all 12 Sonic The Hedgehog 2 achievements worth 200 gamerscore. It takes around 3-4 hours to unlock all of the achievements on Xbox 360.
You won 10 versus zones on Xbox Live.
You got to the Casino Night Zone.
You got one Chaos Emerald.
You played all four multiplayer zones.
You beat Emerald Hill Zone 1 in under 35 seconds in single-player or co-op mode.
You cleared the Emerald Hill Zone 1.
Beat Chemical Plant Zone 1 in under 45 seconds.
Become Super Sonic.
Stay in Super Sonic mode for one minute.
Get all the Chaos Emeralds.
Beat the game in under an hour.
Beat the game.