Here is the full list of all 34 Fall Guys achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Get first place in a racing round 20 times
Win an Episode with a custom Celebration equipped
Clock up 1 hour total time falling
Reach lvl 25 fame during a season
Unlock 10 cosmetic items from the store
Fall for at least 3 seconds before landing on your head
Equip an uncommon or better Body Colour, Pattern, Upper and Lower Costume piece
Equip a rare or legendary Body Colour, Pattern, Upper and Lower Costume piece
Equip your first legendary customization item
Win an Episode as part of a party of 3 or more players
Get first place in a racing round 5 times
Win your first Episode
Qualify from 100 rounds
Reach lvl 10 fame during a season
Get first place in a racing round
Perform an emote just before coming first in a race round
Qualify after a round goes to overtime
Qualify from a racing round despite falling over more than 10 times
Reach terminal velocity
Bump into other Fall Guys 1000 times in total
Qualify from a round without falling over even once
Bump into 3 people while rolling on the ground before getting up
Share a hug with a Fall Guy
Qualify from your first round
Knock someone over
Equip your first cosmetic item
Unlock 50 cosmetic items from the store
Equip a legendary Body Colour, Pattern, Upper and Lower Costume piece
Reach lvl 40 fame during a season
Win 5 Episodes in a row
Win 7 Episodes
Win 20 Episodes
Qualify from 500 rounds
Qualify from a team game with a score of 1