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