OK, I have been able to get to a point where I can read this without sobbing until I am sick, although I will admit to having to stop to grab tissues at several points.
So here is my professional review.
For taking what was available to us as game Lore and canon, and twining it into a satisfying ending: 10/10
For a well constructed plot, in which I could find no holes: 10/10
For being able to orchestrate an actual end-game event with EVERYTHING stacked against you: this thing goes to 11. Or maybe 111.
Actual writing of this story:
This was more of an extended outline, and I mean that in the best sense. I would have altered the pacing a bit. You probably are not familiar with Blake Snyder's Save the Cat and his BeatSheet, but you missed some major beats in the actual writing out of the story. You didn't have a Dark Night of the Soul or Whiff of Death moment that would have made it deeply compelling and would have made this commercial in the best sense, but I can see where that could have been fitted in. And I sense you have not quite grappled with the concept of emotional writing, which would have enriched the prose. Technically (grammar, syntax, yada) you're right there.
Score for the writing itself
Pacing: 8/10
Hitting the Beats: 5/10
Plot: 8/10 (and the only reason I didn't give it 10/10 is I wanted that Whiff of Death)
Technique: 10/10
Emotional evocation: 5/10
Short form: with a little coaching and study of Save the Cat you could go pro. And to put all this together in the short time you had is astonishing. Most pros couldn't do that.
So what you hear from me overall is a standing ovation.