Originally Posted by
aldeayeah
a) Some of the best material in Arc True happens as inner monologues:
- Shiki's inner thoughts when killing Arc.
- Shiki's reaction to Arc dying at Roa's hands.
You can adapt that in a number of ways, like voiceover (laziest but most faithful), scene rewriting, some great acting (a scarce resource) or simply disregarding it.
b) You are going to have to define the amount of exposition your story will need (the least the best). That is going to affect the dialogue as well.
c) If you're sticking to Arc route, in the VN some core stuff is left intentionally vague because it's the subject of other routes. For example, what exactly happened eight years ago. You will probably want to backport some of that material into Arc route, but without going overboard (for example, giving an important role to the maids may be a bad idea).
d) Even though we all love Arihiko, you'll probably want to cut most of the school life part.
EDIT: How I'd do it
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I'd start the script with a faithful reproduction of the [Aoko] prologue, then jump right straight to the day Shiki faints in class. A cliched (but elegant) way to do this would be to have the prologue as a dream scene while sick Shiki's snoozing in class. For maximum economy (and because she's an important character in the route, and the earlier you bring her out the better), you can introduce Ciel right after that, make them meet on Shiki's way to the nurse or something (maybe make her the one who takes Shiki to the infirmary?). Then comes the Arc killing scene, and only after that we meet Akiha and co. From there on it's a vanilla Arc route, starting with the meeting her on the way to school. Nero can be cut entirely, but then you'll have to rewrite stuff because the bit about Shiki being Arc's bodyguard doesn't make much sense if there isn't an immediate threat. Personally I'd leave Nero in, but tone down his abilities. The rest depends on what you want to go for, but you'll probably want to keep the iconic scenes: when Arc nearly eats Shiki, the final showdown in the school and the epilogue. You'll have to explain the whole Shiki/SHIKI situation somewhere along the way (that's Akiha's only important part in the story). I'd wrap the whole thing up with Eclipse but that's just me.
EDIT 2:
Another more radical and IMO better way to structure the beginning would be: start with sick Shiki in school, quickly introduce Ciel, then you can have the Arc killing as soon as minute 2-3! (giving the script a very strong start) Then when Arc's dead and Shiki's all "what?" you cut to title screen/main credits and only then you do the [Aoko] Prologue bit. Then at the end of the prologue we're back to the Arc murder scene, from which the story can proceed normally. The advantage of this is that the prologue is very good but very long, and by delaying it until the main plot is started (with Arc's murder) you can grab the attention of the viewer and never let it go.
EDIT 3: Being a Nero fan, I still would prefer him to show up, even if in an extremely toned-down version, but not because I like him (which I do), but because it's hard for existing characters to take on his role, and his absence may cause cascading changes that end up affecting the story's core.
I mean, with just a bit of sleight of hand you can substitute Soil of Genesis with Nero swallowing Arc into his longcoat. The part with the beasts is harder to do, but maybe you can get away with using just dogs? Or ditch the animals (they're hell to work with) and make him have humanoid minions?
EDIT 4: Ciel's role may be expanded by explaining her role as the former incarnation of Roa, but I wouldn't grab anything else from Ciel's route, particularly not any romantic interest in Shiki. Harem plots are OK for romantic comedies or eroge, but IMO they have no business here.
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Of course these are all just ideas, grab what you like and throw away what you must. I ended up writing far more than I expected, maybe because I've toyed with this kind of idea in the past myself.