Here is the full list of all 26 Mahjong World Contest achievements.
Earn 30 stars
Achieve x5 index
Earn 100.000 points
Earn 500.000 points
Earn 1.000.000 points
Complete the blooming lotus hall
Remove 1000 pairs of tiles
Remove 5000 pairs of tiles
Remove 10000 pairs of tiles
Complete the golden crane hall
Complete the bamboo grove hall
Complete the sakura branch hall
Complete the red phoenix hall
Complete the azure dragon hall
Achieve x10 index
Achieve x15 index
Complete 30 levels with the highest score
Complete 60 levels with the highest score
Complete all the levels with the highest score
Use bonus 50 times
Use bonus 100 times
Use bonus 250 times
Earn 60 stars
Earn 125 stars
Earn 180 stars
Earn 240 stars