Here is the full list of all 42 Only You achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
3 Lvl completed
4 Lvl completed
Music 4
1/3 of the game
5 Lvl completed
Music 5
6 Lvl completed
Music 6
Middle Game
7 Lvl completed
Music 7
8 Lvl completed
Music 8
9 Lvl completed
Music 9
10 Lvl completed
Music 10
11 Lvl completed
Music 11
End Game
12 Lvl completed
Bandit 3 Dead
Music 12
Last Step
Music 3
2 Lvl completed
Pause 2
Pause
Music 2
Bandit 1 Dead
Bandit 2 Dead
First Restart
Game Over
First Death
Go Left
1 Lvl completed
Jump
Go Right
Music 1
Fall
Start Game
Mute