The Mass Transit Add-on for Cities: Skylines has 10 achievements worth 135 gamerscore.
Have 3 monorail lines.
Have 3 blimp lines.
Have 10 blimp lines.
Transport 5,000 passengers with cable cars.
Transport 20,000 passengers with Cable Cars.
Have 3 ferry lines.
Have 15 ferry lines.
Have 10 monorail lines.
Have a Ferry, Bus Exchange Stop, MetroMonorailTrain Hub, Monorail-Bus Hub and Multiplatform Station
Win all three Mass Transit scenarios.