I disagree. Having "the" before a non-english word seems very awkward. Sure, without it, shikagami sounds like a proper noun, but it results in a title i (a person unfamiliar with the franchise) would accept. With "the" in front, it makes me think "what the hell's a shikagami, and why wasn't that word translated to english?"
I don't see a problem with having "the" before a non-English word. As you say, the absence of "the" makes "shikigami" sound like a proper noun, which it isn't. Also, "the" often appears before other Japanese phrases like "ninja" (e.g. "Mark of the Ninja") and "samurai" (e.g. "The Way of the Samurai"). "Shikigami" is less well-established, which might be what makes it sound awkward.
I think your second point is a good one, though. What the hell is
a shikigami? One answer is this: "a god of rites; a spirit that is said to perform marvelous, phantasmagoric tricks under the orders of a yin-yang diviner" (from Kojien
). Another answer is, "the thing(s?) in the game". The point is, though, like "ninja" and "samurai", there's not really an equivalent for "shikigami" in English, so it's probably best to use the word as is. And IMO, "the Shikigami" is the most appropriate way to render it in English.
Well, specifically I mean how to edit that vertically oriented screen. Castle of Shikigami's staying, series tradition.
(I was briefly tempted to do 'The Castle of Shikigami', but if it ain't broke...)
As for the series' title being tradition, maybe I'm kind of a boat-rocker when it comes to translations, but my general rule these days is: screw tradition when tradition is wrong. There's something to said for a series to be easily recognizable by its fans, but at the same time, I think one of the goals of fan translation should be to improve upon the shortcomings of past translations.
Also, no offense, but I think "The Castle of Shikigami" makes "shikigami" sound even more like a proper noun.
I'm afraid I can't help you on how to redesign that screen. The best I can do is gripe about the title.
I guess I've spoken my piece on this, so I'll let it go now.