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.
Don't save the Man in Black.
Win The One Tournament.
Defeat the helicopter boss.
Travel to the secret moon base.
Defeat the Ether boss.
Complete the auto map by visiting every room in the mansion.
Find all the alternate title screen skins.
Find all the secret rooms in the mansion.
Clean 1000000 things.
Push all the rubber ducks into the water in the Laundry Room.
Defeat the Fire boss.
Catch 200 objects.
Defeat the Water boss.
Die 1000 times.
Get the kids blamed for shop lifting.
Watch a train arrive and leave at any station.
Defeat the Air boss.
Find a secret room in the mansion.
Buy all possible shop items..
Find an alternate title screen skin.
Defeat the Earth boss.
Reunite with Heather and the Old Lady.
Go on a most excellent adventure with the Professor.
Meet up with Alice and Sim.
Read 15 teletext pages.
Score 100 baskets in total.
Get the high score on all the arcade games.
Earn £10000 from jobs, junk yards and other winnings.
Kidnap Mr Deck from the TV Studio.
Clean 100000 things.
Run the BASIC program everybody knows and loves...
Take your first train ride.
Help to sort the post.
Help to make bricks.
Buy an item from a shop.
Play an arcade game.
Earn £1000 from jobs, junk yards and other winnings.
Earn £100 from jobs, junk yards and other winnings.
Help to wash dishes.
Spring Logan from prison.
Empty 10 bins.
Learn to play the drums.
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.
Clean 10000 things.
Return the blind man's cat.
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.