Here is the full list of all 31 Kingdom Eighties achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Complete the game on Hard
Complete a level with no more than 20 kids
Survive for 50 days in one level
Uncredited professional BMX rider making it rain coins
Clear all the trees on any level
Wait for the bus
Destroy a portal on Peaceful
Complete Episode IV
Get something back from the past
Lose 80 coins to the waters
Rainy day at Paradise Estate with Rainbows in tow
Destroy a portal around the mall
Complete Episode III
Complete a level with only two workers
Defeat 10 greed with a machine gun
Get eaten by a shark
Destroy a portal on the streets
Complete Episode II
Slap a monster truck
Lose the Crown, and take it back
Recruit someone smart
Complete Episode I
Enter a cave
Destroy another portal
Destroy a portal in a forest
Recruit someone handy
Recruit someone athletic
Find the missing trophy
Recruit someone friendly
Complete the game on Cursed
Complete the game in 50 days or less