Here is the full list of all 20 Antigraviator achievements.
You lapped someone
Play all the maps in the game
Play 400 quick races
Compete in 400 death races
Play 400 countdown races
Set 500 traps that get triggered
Buy all items
Finish the Legends League
Break the soundbarrier
Unlock the crocco
Unlock the X1Z1
Make the bridge jump in Serpentine Valley
Finish your first League
Win a race with second place finishing within 0.5 seconds of you
Buy your first item
Keep a constant speed
Avoid taking damage during a race
Finish your first race
Win an online race
Do not die during a race