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