Here is the full list of all 16 PLANET ALPHA achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Resting by the pond
Can't compete with the trees
Like a big family
What lies beyond
Another time another opportunity
Falling is not an option
Curiosity is key
Collecting the fourth artifact
It was never meant to happen
Don't fight the flow
Collecting the third artifact
Collecting the second artifact
Downwards is the new upwards
Slipping through the cracks
Collecting the first artifact
How did they get it up there