Here is the full list of all 11 Sword of the Stars: The Pit Demo achievements.
You completed the demo tutorial! So go try the demo. Then, you know, buy the full game. This is just the tip of the iceberg.
You've survived past Floor 5 on Easy.
You've survived past Floor 5 on Normal.
You've survived past Floor 5 on Hard.
You've survived past Floor 5 on Insane!
You made yourself a blandwich. Rumor has it they are 10% less bland in the full game.
You've survived to Floor 10 on Easy.
You've survived to Floor 10 on Normal.
You've survived to Floor 10 on Hard.
You've survived to Floor 10 on Insane!
You completed the tutorial and got to play with the psionic powers a bit. There's lots more in the full game.