Here is the full list of all 21 Scrap Garden - The Day Before achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Eliminate 100 enemies
Finish the game without being damaged
Eliminate 50 enemies
Break 100 boxes
Find old arcade machine
Break 50 boxes
Start the game
Finish the game
Beat the Boss!
Find the Engineer
Break into the computer.
Fix the water pipes
Find something in the collector
Collect 500 spares
Eliminate 10 enemies
Jump into the water
Break 10 boxes
Collect 300 spares
Collect 100 spares
Collect 10 spares
Collect 50 spares