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