The major factor I considered was just how to portray the Dragonborn, considering that, as the player, you can be a Dragon born of any race or gender. I finally settled on the fact that since the Dragonborn is a Nord legend, and given the subject matter and culture of the time period many would assume the hero to be male, that a younger Nord male would fit the bill fine enough. Probably much like the generic male character they used in the trailer and promotional art. It would be wonderful if the hero could instead be a heroine, but for some reason most audiences can't get behind a female protagonist lest it be in come B-list chick flick, sadly enough.
Taking into consideration that the entire story would take place in his homeland of Skyrim, it would eliminate the need for any sort of elaboration on the hero's home/past/culture as it can all be learned and inferred throughout the film. Say for example the Dragonborn was portrayed as a Redguard, or Bosmer. There would have to be at least some part of the film dedicated to explaining life and culture in Hammerfell or Valenwood to allow the audience a better understanding of the character. All-in-all, a Nord Dragonborn would cut down on a lot of unnecessary material.
[Perhaps, potential spoilers for some beyond this point. Read at your own caution.]
When it comes to the storyline, if they intended to make it one, standalone film a lot of fluff from the game would have to be cut. By that I absolutely mean cutting off all the hero's participation in the various guilds. No Thieve's Guild, no Dark Brotherhood, no College of Winterhold. That's not to say take them out of the equation entirely, but I can't see as to how it's possible to fit the Dragonborn becoming Leader of the Thieve's Guild, Listner of the Dark Brotherhood, and Arch Mage of the college all in one film. What would be nice, is if they were still included, such as the Thieve's Guild being a looming threat in Riften, the Dark Brotherhood following through with the assassination of the Emperor, and the College still being the subject of disdain and skepticism throughout Winterhold and much of Skyrim. It would be very possible to keep them, and include their major points in a single plot without over-cluttering the storyline with long, drawn out involvement.
The only guild I think could be involved to any great length would be the Companions, and only if much of their plot line is trimmed down. The Dragonborn wouldn't necessarily have to join their ranks, but I could see something along the lines of them looking to the Dragonborn as a sort of "leader in tough times" after the death of Kodlak happening if it could be scripted well enough. The most prolific of the Companions members are Nords, anyway, so it would make sense plot wise for them to want to look to and support the Dragonborn. Whiterun is a proverbial "swing state" when it comes to the Civil War, so it would make sense that a large portion of the film plot would take place there, and around that area. As the Companions are already there and in the thick of things, it wouldn't make much sense to exclude them altogether.
In my opinion, it would be best to trim the focus entirely down to the main story line, and the Civil War. I think both could be covered fairly enough to create a decent plot. As with many players, you're going to have audience members who identify with the Imperials and you're going to have those who side with the Stormcloak rebellion, and both are going to want the Dragonborn to side with the one they prefer. Now, as I considered it, the Dragonborn is a hero of the people and not the hero of the Empire nor the savoir of the Stormcloaks. They player in-game may choose one side over the other, but ultimately it is not required to do so. If you have the hero take sides, you're going to ultimately end up with half of the audience who no longer supports him, which would be murder for the film. If it could be pulled off, (since, as I mentioned the Dragonborn is a hero of all people) having the hero aid both sides throughout the story, both fairly, equally and unbiased without ultimately choosing to side with one or the other would really emphasize the "people's hero" aspect of the character.
Forgive me for my over analyzation, and boring you with my rant. I considered film making as a career choice, at one point in time, so I still get passionate about it.
