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.
Read 15 teletext pages.
Die 1000 times.
Score 100 baskets in total.
Find all the alternate title screen skins.
Push all the rubber ducks into the water in the Laundry Room.
Complete the game.
Reach the end of the game having cleaned one million things.
Run the BASIC program everybody knows and loves...
Clean 1000000 things.
Find all the secret rooms in the mansion.
Complete the auto map by visiting every room in the mansion.
Watch a train arrive and leave at any station.
Find a secret room in the mansion.
Get the high score on all the arcade games.
Catch 200 objects.
Get the kids blamed for shop lifting.
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.
Defeat the Fire boss.
Defeat the Air boss.
Find an alternate title screen skin.
Defeat the Water boss.
Buy all possible shop items..
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.
Kidnap Mr Deck from the TV Studio.
Clean 100000 things.
Take your first train ride.
Play an arcade game.
Earn £10000 from jobs, junk yards and other winnings.
Buy an item from a shop.
Earn £1000 from jobs, junk yards and other winnings.
Help to sort the post.
Help to make bricks.
Earn £100 from jobs, junk yards and other winnings.
Help to wash dishes.
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?
Return the blind man's cat.
Clean 10000 things.
Rescue the family from the burning house.
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.