To unlock five bonus stages, earn 25 gold trophies.
To unlock 14 secret stages, collect the 45 Green Crystals. There is one Green Crystal in each regular stage. Also, to unlock a 15th stage, beat all five bonus stages.
To unlock 20 balls, beat all 45 stages and the 15 secret stages.
To unlock all music, beat all the stages.
To unlock Mirror mode, beat all 45 stages.
Unlock the following Balls by performing the corresponding tasks:
BALL – HOW TO UNLOCK
Car Crush Ball – Beat the first Mirror mode stage and collect the Yellow Gem.
Flash Ball – Beat the last Normal mode stage and collect the Yellow Gem.
Galaxy Ball – Beat the first Night Zone stage and collect the Yellow Gem.
UFO Ball – Beat the last Mirror mode stage and collect the Yellow Gem.
100% game completion:
To achieve 100% game completion, beat all regular, bonus and secret stages in standard and Mirror modes, and unlock all Balls and music.
Green Crystals hint:
Every green crystal is either hidden, hard to get, or both.