The Storm Island Add-on for Forza Horizon 2 has 23 achievements worth 500 gamerscore.
Arrive on Storm Island.
Win your first Storm Island Championship.
Win 5 Storm Island Championships.
Win the Storm Island Finale.
Win an Event in the Mitsubishi Galant.
Win an Event in the Robby Gordon #7 SST.
Win an event in the Ford Ranger.
Win an event in the '81 Ford Fiesta.
Win an event in the MG Metro R4.
Find and restore a Barn Find on Storm Island.
Complete your first Storm Island Bucket List Challenge.
Complete every Storm Island Bucket List Challenge.
Complete every Co-op Storm Island Bucket List Challenge.
Collect every Storm Island Bonus Board.
Drive every Road on Storm Island.
Bank a Skill Chain of 100,000 points on Storm Island.
Start a race with Off-Road tires, suspension, and transmission on Storm Island.
Win 5 events in stormy conditions.
Complete 50 Online Events on Storm Island.
Complete every Storm Island Championship.
Complete your first Gauntlet Event.
Visit the Storm Island Car Meet and win 3 Showdowns.
Win every Gauntlet Event.