Here is the full list of all 15 Rhythmic Retro Racer achievements.
You unlocked your first car!
You unlocked your 3rd car
You unlocked your 5th car
You've completed cyberpunk level!
You've completed nightdrive level!
You've completed abstractum level!
You've completed volcano level!
You've completed highway level!
You tried very hard level!
You've completed abstractum level in hardmode!
You've completed futurama level in hardmode!
You've completed volcano level in hardmode!
You've completed highway level in hardmode!
You've completed nightdrive level in hardmode!