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