Here is the full list of all 58 Horace achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Complete all other achievements.
Save the Man in Black.
Complete the game.
Reach the end of the game having cleaned one million things.
Die 1000 times.
Find all the secret rooms in the mansion.
Don't save the Man in Black.
Complete the auto map by visiting every room in the mansion.
Win The One Tournament.
Defeat the helicopter boss.
Travel to the secret moon base.
Defeat the Ether boss.
Clean 1000000 things.
Find all the alternate title screen skins.
Push all the rubber ducks into the water in the Laundry Room.
Defeat the Water boss.
Defeat the Fire boss.
Catch 200 objects.
Defeat the Air boss.
Read 15 teletext pages.
Find an alternate title screen skin.
Get the high score on all the arcade games.
Buy all possible shop items..
Find a secret room in the mansion.
Defeat the Earth boss.
Reunite with Heather and the Old Lady.
Kidnap Mr Deck from the TV Studio.
Go on a most excellent adventure with the Professor.
Score 100 baskets in total.
Clean 100000 things.
Run the BASIC program everybody knows and loves...
Meet up with Alice and Sim.
Take your first train ride.
Watch a train arrive and leave at any station.
Earn £10000 from jobs, junk yards and other winnings.
Help to wash dishes.
Play an arcade game.
Get the kids blamed for shop lifting.
Buy an item from a shop.
Help to make bricks.
Earn £1000 from jobs, junk yards and other winnings.
Earn £100 from jobs, junk yards and other winnings.
Help to sort the post.
Spring Logan from prison.
Learn to play the drums.
Empty 10 bins.
Defeat the Nanobot Boss.
Defeat the K-Bot 100 Boss.
Use the Atlas Gloves to tidy up the village hall.
Of dead Old Men?
Rescue the family from the burning house.
Return the blind man's cat.
Clean 10000 things.
Venture out of the mansion.
Climb walls with the Shoees for the first time.
Clean 1000 things.
Clean up your first thing.
Completed basic robot training.