Full list of all 15 Dr. Atominus achievements worth 2,000 gamerscore. It takes around 0-0.5 hours to unlock all of the achievements in the base game.
The base game contains 10 achievements worth 1,000 Gamerscore, and there is 1 DLC pack containing 5 achievements worth 1,000 Gamerscore.
Discover the library
Destroy 10 enemies
Gain 50 coins
Press the button on the floor
Gain an electron
Gain 10 coins
Gain 1 coin
Destroy 1 enemy
Gain a key
Discover a PC
Survived the drowning attempt
Destroyed 5 fish
Entered the water zone
Found a medicine tube
You have defeated the first boss