Here is the full list of all 43 Only One achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Go Right
Go Left
End Game
12 Lvl completed
Mute
Music 12
Last Step
11 Lvl completed
Music 11
10 Lvl completed
Music 10
9 Lvl completed
Music 9
8 Lvl completed
Skeleton 1 Dead
Skeleton 2 Dead
Music 8
7 Lvl completed
Music 7
6 Lvl completed
Music 6
Middle Game
5 Lvl completed
Music 5
4 Lvl completed
Music 4
1/3 of the game
3 Lvl completed
Music 3
2 Lvl completed
Music 2
Bandit 1 Dead
Bandit 2 Dead
Pause 2
Pause
1 Lvl completed
First Restart
Game Over
First Death
Jump
Music 1
Fall
Start Game