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