Is this ever a valid way to start a interactive story? If so, how could it ever be pulled off? Are there any good examples of this?
By starting at the end, I mean to show a scene that you will inevitably be at towards the end of the story.
It would be hard to do a nonlinear story if the ending is fixed, but one way to do it would to make the player be different characters in the scene depending on their choices, e.g. one ending has you as the murderer, another as the victim and another as a witness.
Of course you could simply have many ways of reaching a similar point, giving the event different context and motivation for the player, e.g. you slay the dragon because it killed your family, to rescue someone it holds captive or to get the bounty on it.
I was thinking of making the final scene fixed, but the reason for the main character being there will be based of the choices made when the main character is thinking back on how he got to that point.
You could make the beginning scene very vague, like; "So, I'm just about to die and I'm looking back over my life and wondering if I could've done things better." ... Or something along those lines.
When I'm writing the story in what is basically the PC's flashbacks, do I have to use past tense in the writing? It would seem awkward to me if I did.
When describing the scenario, yes, but you could use present tense in the flashback itself.
I remember the first time John offered me a banana...it had brown, rotton flesh.
John: Hey, want a banana?
You: Fuck you John!
You could set it so the story starts right before the ending. The flashbacks as you approach the 'final boss' area will determine how the 'boss battle' goes.
So if your story was about killing a tyrant and your flashback choices were evil then your ending would just be replacing the tyrant as a more powerful tyrant.
Yeah, not the very end though. Like, maybe the middle of some final battle where the good guy and bad guy are standing off. And then you have a link saying "what started all of this?" or "How it all began". Then start the story.