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