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.
Collecting the fourth artifact
It was never meant to happen
Like a big family
Another time another opportunity
Don't fight the flow
Curiosity is key
Can't compete with the trees
Collecting the third artifact
Downwards is the new upwards
What lies beyond
Collecting the second artifact
Slipping through the cracks
Collecting the first artifact
Falling is not an option
Resting by the pond
How did they get it up there