There are 12 achievements worth a total of 200 points
You collected a Chaos Emerald.
You scored 20,000 points.
You scored 40,000 points.
You collected 50 rings.
You got a blue gumball.
You scored 80,000 points.
You ran across water.
You finished the Hydrocity Zone.
You finished the Marble Garden Zone.
You completed the Icecap Zone.
You finished the game.
You collected all seven Chaos Emeralds.