Here is the full list of all 24 SteamWorld Dig achievements. It takes around 10-12 hours to unlock all of the achievements on Windows.
Complete the game with more than 20000 gold collected in total.
Complete the game with more than 150 orbs collected in total.
Immortalization of a destructible steambot.
Find all secret areas in the caves.
Reach the bottom of the world.
Find and sell 16 Dark Matter ores at the same time.
Destroy a laser box.
Defeat 10 mecha trilobites before they wake up.
You found Vectron!
Destroy two generators before entering Vectron.
Find and sell 8 Uranium ores at the same time.
Defeat 10 shiners before they wake up.
Buy from all of Tumbleton's shops.
Defeat a turtle submerged in water.
You found the Old World!
Defeat 10 trilobites before they wake up.
Find and sell 8 Trashium ores at the same time.
You found Archaea!
Complete the game in less than 2 hours, 30 minutes.
Complete the game without getting killed once.
Get all four gold stars in the same playthrough.
Crush 10 enemies with falling blocks.
Maximize all upgrades.
Dig out 15000 tiles.