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.
Die 1000 times.
Find all the alternate title screen skins.
Clean 1000000 things.
Save the Man in Black.
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 secret rooms in the mansion.
Defeat the Fire boss.
Buy all possible shop items..
Defeat the Water boss.
Get the kids blamed for shop lifting.
Read 15 teletext pages.
Catch 200 objects.
Defeat the Earth boss.
Find a secret room in the mansion.
Defeat the Air boss.
Find an alternate title screen skin.
Push all the rubber ducks into the water in the Laundry Room.
Reunite with Heather and the Old Lady.
Go on a most excellent adventure with the Professor.
Score 100 baskets in total.
Clean 100000 things.
Kidnap Mr Deck from the TV Studio.
Get the high score on all the arcade games.
Run the BASIC program everybody knows and loves...
Meet up with Alice and Sim.
Earn £10000 from jobs, junk yards and other winnings.
Watch a train arrive and leave at any station.
Take your first train ride.
Buy an item from a shop.
Help to sort the post.
Earn £1000 from jobs, junk yards and other winnings.
Help to make bricks.
Play an arcade game.
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.
Return the blind man's cat.
Of dead Old Men?
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.