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