Here is the full list of all 15 Roller Coaster Rampage achievements.
Achieve 16x Multiplier 16 Times
Complete 100 Outside Stunts
Build 100 Complete Coasters
Complete 15 Corkscrews
Build 50 Loops
Receive a Gold Star
Complete a Loop
Complete 1 Coaster in Freeride
Perform a Barrel Roll
Unlock All 30 Levels
Collect 1000 Gems
Complete All 30 Levels
Destroy the Seamonster 8 Times
Link 250 Track Sections
Receive Gold Stars For All 30 Levels