Here is the full list of all 31 Tic-Tac-Letters by POWGI (Asia) trophies - there are 4 bronze, 23 silver, 3 gold and 1 platinum.
Collect all the trophies
Solve Fs and Us
Use Hint 100 times
Solve Fs and Ms
Spend at least 60 seconds considering something futile
Solve Bs and Gs
Solve Ts and As
Solve Bs and Os
Solve Es and Gs
Solve Bs and As
Solve Is and Ts
Solve Hs and Es
Solve Gs and Ns
Solve Ls and Os
Solve Ms and Hs
Solve Ds and Os
Solve Us and Ps
Solve Ts and Os
Solve Ys and Es
Solve Es and Xs
Solve As and Hs
Solve Ys and Rs
Solve Cs and Us
Solve Ps and Is
Solve your first Hard puzzle
Solve Xs and Os
Solve a puzzle in under 60 seconds
Solve your first Beginner puzzle
Solve a puzzle without making a single mistake
Solve a puzzle without using Fix or Hint
Read the instructions to the end