Here is the full list of all 20 GNOG achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Test the astronaut for space sickness
Please don't bother the amphibians
Complete VORT-X
Complete SUB-01
Discover what lurks below
Complete FRG-Y
Finish the game
Complete HOM-3
Complete EATER
Complete CANDY
Complete LAB-O
Complete LOG
Complete PURP-L
Unlock every level
Leave no trace
Keep the kitchen clean
Watch what you eat
Daydream at the blackboard
Leave no worm behind
Experiment in the studio