Here is the full list of all 71 Ra² achievements.
Fail at a level
Complete every level of Sector D
Complete every level of Sector C
Complete every level of Sector B
Get a time higher than two minutes at any level
Switch to a next level
Check the controls
Complete every level of Sector A
Complete every level of Sector E
Complete every level of Sector F
Complete every level of Sector G
Complete every level of Sector H
Complete every level of Sector I
Complete every level of Sector J
Complete every level of Sector K
Complete every level of Sector L
Complete every level of Sector M
Complete every level of Sector N
Complete every level of Sector O
Complete every level of Sector P
Complete every level of Sector Q
Complete every level of Sector R
Complete every level of Sector S
Complete every level of Sector T
Complete every level of Sector U
Complete every level of Sector V
Complete every level of Sector W
Complete every level of Sector X
Complete every level of Sector Y
Complete every level of Sector Z
Fail hundred times
Get three points on any level
Beat your own highscore
Get a time higher than your highscore
Switch to a previous level
Get 3 points at every level
Get 3 points at every level of Sector A
Get 3 points at every level of Sector B
Get 3 points at every level of Sector C
Get 3 points at every level of Sector D
Get 3 points at every level of Sector E
Get 3 points at every level of Sector F
Get 3 points at every level of Sector G
Get 3 points at every level of Sector H
Get 3 points at every level of Sector I
Get 3 points at every level of Sector J
Get 3 points at every level of Sector K
Get 3 points at every level of Sector L
Get 3 points at every level of Sector M
Get 3 points at every level of Sector N
Get 3 points at every level of Sector O
Get 3 points at every level of Sector P
Get 3 points at every level of Sector Q
Get 3 points at every level of Sector R
Get 3 points at every level of Sector S
Get 3 points at every level of Sector T
Get 3 points at every level of Sector U
Get 3 points at every level of Sector V
Get 3 points at every level of Sector W
Get 3 points at every level of Sector X
Get 3 points at every level of Sector Y
Get 3 points at every level of Sector Z
Get a time less than 10 seconds at any level
Skip to a next music track
Skip to a previous music track
Complete 20% of the game
Complete 40% of the game
Complete 60% of the game
Complete 80% of the game
Get the same time as your highscore (in seconds)
Get 8x the same time as your highscore (in seconds)