Here is the full list of all 63 Earth Overclocked achievements.
Run into the instant death spikes
Defeat Meiun
Finish a run in the Scientist Suit
Finish a run in the Ninja Suit
Finish a run in the Gym Suit
Finish a run in the Magnet Suit
Finish Earth Unleashed in the Scientist Suit
Finish Earth Unleashed in the Ninja Suit
Finish Earth Unleashed in the Gym Suit
Finish Earth Unleashed in the Magnet Suit
Collect all of the contents in the Mega Slot Chests
Defeat the rare Mothguy
Defeat the rare Chucab
Defeat the rare Slendy
Defeat the rare Benny
Defeat the rare Jef
Beat the final boss
Beat the Time Empress
Buy the most expensive weapon from a merchant
Score 200,000 points
Finish a run in the Birthday Suit
Use the Sheep weapon on an enemy
Finish Earth Unleashed in the Birthday Suit
Score 50,000 with the Scientist Suit
Score 50,000 with the Ninja Suit
Score 50,000 with the Gym Suit
Score 50,000 with the Magnet Suit
Defeat a Wumbo Blob
Defeat the Blob Bros.
Defeat Treebot
Score 50,000 with the Birthday Suit
Yep. (only need the Singleplayer ones)
Defeat Skeleking
Defeat the Night Emperor
Defeat the Soul of Raynald
Defeat Zombakuto
Defeat a Tree Monster
Defeat Foreman Jack
Defeat a Bombcano
Defeat Meteor Bob
Defeat Mystery
Defeat Zombakuto BW
Defeat a Sandstorm
Defeat a Yeti
Defeat Frozen Bones
Defeat a Crystal Heart
Defeat the Royal Dillos
Lose 50 runs
Finish a run in under 15 in-game minutes
Finish a run in under 12 in-game minutes
Finish a run in under 10 in-game minutes
Delay the Apocalypse by 150 seconds in one run
Delay the Apocalypse by 4 minutes in one run
Delay the Apocalypse by 6 minutes in one run
Defeat Elemental Meiun
In the Scientist suit, complete a run without using the revive potion
In the Ninja suit, defeat a boss without using either attack button
In the Magnet suit, have 15 hearts follow you at once
In the Gym suit, defeat a boss with both weapons at full weight
Defeat the special Gold Blob
Defeat one of Meiun's Advocates
Take no damage in a run
Take no damage in a run in Earth Unleashed