Here is the full list of all 55 HROT achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Complete 6 different levels on Very High Difficulty
Check the simulator
Complete all three episodes
Complete episode 3
Give a gastroscopy
Burn 4 monsters with one bottle
Kill or damage 10 monsters with landmines
Find Tuzex vouchers
Find a postcard from the creators of Project Warlock 2
Surprise the newt in the cabin
Hit the enemy with a kicked grenade
Kill a monster by knocking it off somewhere high with the footkick
I really like this random stuff
Have a gastroscopy
Early Access sauna is a cold place
Free 4 Ratters
Shoot down a flying pigeon
Locate the secret level
Pet two dogs
Waste three minutes watching the model railway
Get past wave 15 in Endless Mode
Get past wave 10 in Endless Mode
Survive wave 5 in Endless Mode
A lot of wine
Complete episode 2
Get through a level without damage
Clean all mess after the Degustation
Find all plates in the Granny's Valley and bring them to the Degustation
Anger the bees and run away
Kill 35 monster types
Start the mining train
Find 50 different secrets
Kill Headsman in air during jump
Gottwald's body missing
Discover a secret of Vyšehrad Castle
Find a second pistol
Run over 10 monsters
Find all secrets in a level
Kill 5 monsters with a sickle in a row without damage
Complete episode 1
Kill 500 monsters in total
Gib a horse
Hit an enemy with the soccer ball
Achieve a score of 200 points on a handheld game
Kill all monsters in a level