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
Finish the game
Complete LAB-O
Daydream at the blackboard
Unlock every level
Complete LOG
Leave no worm behind
Complete VORT-X
Complete SUB-01
Discover what lurks below
Complete HOM-3
Complete CANDY
Complete EATER
Complete PURP-L
Experiment in the studio
Complete FRG-Y
Leave no trace
Please don't bother the amphibians
Keep the kitchen clean
Watch what you eat