The MC's death depends on the choices you make. There are 3 possible endings.
1 bad (as DakotaJack found), and 2 good. There is a bit of difference in the good endings but nothing major. You need to make better choices.
If you like to have the story narrated I would recommend the following youTuber (he did all of Adastra, Khemia, and Interea as well as other VNs). I think he does a great job:
https://www.youtube.com/user/Lynx890/playlists
I don't play these type of games to see the bad ending first (as some like to do), I just play according to my nature. As such I don't know all the details except for what has been posted in the forums. Also I don't like to do spoilers so you will have to dig through the forum for more answers. That said however, the ending you got is one of the good ones from my understanding.
You might also find some answer in the Khemia and Interea forums as well since they often discuss players experiences from Adastra.