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