Here is the full list of all 20 Alto's Adventure (Windows) achievements worth 1,000 gamerscore.
You recovered 100,000 llamas (cumulative).
you rode for 10,000,000m (cumulative).
You played as Tupa.
You snowboarded for 365 in-game days (cumulative).
you rode for 1,000,000m (cumulative).
You played as Felipe.
you recovered 10,000 llamas (cumulative).
You played as Izel.
You recovered 1,000 llamas (cumulative).
You rode for 10,000m (cumulative).
You rode for 100,000m (cumulative).
You played as Paz.
You snowboarded for 30 in-game days (cumulative).
You snowboarded for seven in-game days (cumulative).
You played as Maya.
Your board stuck straight up after a crash. Oops!
You played one run with Alto.
You completed the tutorial.
Snowboard for five in-game years (cumulative).
Complete all 180 goals.