Here is the full list of all 13 Lonely Astronaut achievements.
Keep going.
You are a leaf on the wind.
Why is the existential dread always gone?
Like a saltine, but Earthier.
You're gamma ray bursting with love!
Hard to be pro-life as a skeleton.
You are become Dead, Destroyer of Worlds.
Romilly won't be happy when you get back late.
You're a skelly, Tom! Score 1000 points.
Life is usually like golf: You wanna die the fewest times possible. You seem to have taken a different approach. Score 10,000 points.
They lose, and you win! But you're dead though. So not really. Score 50,000 points.
Imagine the trillions you've killed already! Imploding the lifeblood of the Universe means nothing! Everyone is a huge fan. <3 Score 250,000 points.
Your empty sockets fill forever with tears. You cannot stop. There is no end. You've got a sick score though, so that's cool. Score 1,000,000 points.