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