Here is the full list of all 14 RGB Rush achievements.
Unlock the HEX gamemode
Attempt to press the enter button after the timer has ended
Play hex single in blind and timed mode
Score a point by typing a colour in correctly
Type in a number that's too large
Move a slider while holding spacebar to adjust all sliders at once. I'm proud of you for paying attention in the tutorial.
Used the arrow keys to set a slider precisely
Press enter before you've even chosen a colour
Exit a game without scoring any points
Press exit to menu, but then don't press confirm because you want to keep playing
Actually tried the tutorial
Make a guess with 0% accuracy
Guess a colour exactly (HEX single not included)
Play 100 games in total