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