Here is the full list of all 34 Atomic 79 achievements.
Kill 1,000 Skeltins
Survive 1 minute in the crater
Kill 10,000 Skeltins
Kill 100 Gold Skeltins
Kill 500 Red Skeltins
Kill 300 Toxic Skeltins
Kill 1,000 Skells
Kill 250 Red Skells
Kill 200 Toxic Skells
Kill 500 Bone Balls
Kill 1 Skell Lord
Kill 5 Skell Lords
Kill 20 enemies with a single grenade
Kill 10 enemies with a single toxic enemy death explosion
What's he doing here?!
Survive 2 minutes in the crater
Survive 3 minutes in the crater
Survive 4 minutes in the crater
Survive 5 minutes in the crater
Survive 6 minutes in the crater
Survive an expedition
Fully upgrade one weapon
Fully upgrade all weapons
Have a single deposit of 200 gold or more
Drop 200 gold on one death
Gain 5,000 gold total
Shoot Frand 50 times in one expedition, you monster!
Luck into the Golden Skeltin Anomaly
Survive the Bone Ball Anomaly
Survive the Boom/Zoom Anomaly
Survive the Skell only Anomaly
Survive the "Overwhelming Darkness" Anomaly
Find an Anomalous Skull
Bring Bloop back to the Atomic 79