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