Here is the full list of all 12 FunTown Mahjong achievements worth 200 gamerscore.
Win 100 games in Ranked Match mode.
Win a mahjong hand with an 8-point category.
Win a mahjong hand with a 4-point or 5-point category.
Win a game session where other players received negative grades.
Complete a Mahjong hand 10 times in Ranked Match mode.
Complete a game session without discarding a tile that allows another player to win.
Complete a multiplayer match.
Complete the Tutorial.
Play 100 complete ranked matches.
Win a mahjong hand 100 times by self-pick in Ranked Match mode.
Accumulated 10,000 scores in Ranked Match mode.
Win a mahjong hand 8 times by self-pick in a single game session.