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