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