The Empire of the Sky Add-on for Trials Fusion has 5 achievements worth 250 gamerscore.
Gatecrash an apartment on 'Winter Getaway' and complete their arcade game
Complete all 3 challenges on 'Stratosphere' in a single run, with less than 15 faults
Destroy all the ecosystems on 'Eden' in a single run
Find all 3 squirrels on Empire of the Sky
Pass all tracks on Empire of the Sky