I’ll give the code another look, thanks for helping me track down inevitable sleep deprivation-induced slips :)
But, if you’d like to know everything about possible endings:
[SPOILERS]
There isn’t a happy ending where Arbor, or Sam, can be saved. I thought about putting one in, but I wanted to focus on having the player make tough choices in the face of an impossible situation, and I felt that including the possibility of rescuing Sam would detract from that.
So, the different endings are how Sam reacts to your last letter (if you send one), and that depends on the choices made in the previous letters.
I'd be interested to hear thoughts on whether that just feels unsatisfying though.