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
Find Tuzex vouchers
Kill or damage 10 monsters with landmines
Burn 4 monsters with one bottle
Find a postcard from the creators of Project Warlock 2
Hit the enemy with a kicked grenade
Have a gastroscopy
Kill a monster by knocking it off somewhere high with the footkick
I really like this random stuff
Surprise the newt in the cabin
Early Access sauna is a cold place
Shoot down a flying pigeon
Free 4 Ratters
Locate the secret level
Pet two dogs
Waste three minutes watching the model railway
Get past wave 15 in Endless Mode
Kill 35 monster types
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
Find 50 different secrets
Complete episode 2
Get past wave 10 in Endless Mode
Achieve a score of 200 points on a handheld game
Get through a level without damage
Find all secrets in a level
Survive wave 5 in Endless Mode
A lot of wine
Start the mining train
Kill Headsman in air during jump
Complete episode 1
Gottwald's body missing
Find a second pistol
Gib a horse
Kill 500 monsters in total
Discover a secret of Vyšehrad Castle
Hit an enemy with the soccer ball
Kill all monsters in a level
Run over 10 monsters
Kill 5 monsters with a sickle in a row without damage