If you want to avoid spoilers you can just watch the first cutscene in the video. I want to say it's Shakespearian but the dialect seems older than that even.
I'm not very knowledgeable about it (I'm sure many around here are), but I'd say Middle English. Shakespeare was writing I believe right at the end of the Middle English period, when it was giving way to Modern English. And of course he was essentially creating it. But there are many things written in Middle English. Certain Bible translations for one thing. I think the King James? I'm not sure if Beowulf was in Middle or Old English. Ok, I've exceeded my knowledge on the subject (probably before I finished writing that).
Pseudo-Early Modern English. Essentially modern English with a few archaic constructs and words thrown in.
According to reddit: "First, I should probably clear up some possible misconceptions. It’s a completely fictional dialect: English was never spoken like this. However, the fictional dialect is completely grounded in historical English. It essentially takes Early Modern English grammar and vocabulary and blends it with a watered-down version of Middle English’s morphology, which, in the case of nouns, is in turn based on Old English’s grammatical gender and, for loaned French nouns that came about as a result of the Norman conquest of England, French’s grammatical gender. It is not based primarily on Middle or Old English. That’s a common misconception, but it’s important to understand that, because H’aanit’s dialect is almost completely comprehensible, it’s more rightly classified as a variation of Early Modern English." He then goes into the linguistic details of the languages its based off of. You can read the full post here
Beowulf was Old English. An example of Middle English is Chaucer's Canterbury Tales (it doesn't even sound like English to me and was a chore to learn). But yes, its more common than Old English
D'oh! I should have realized it's based more on Early Modern. Yes, I've struggled with Chaucer, and it doesn't seem remotely like English! Some foreign languages are easier to figure out.
Yeah to me it's not far from Modern English and a lot more understandable than Chaucer or Shakespeare. If you like this style of speaking, there is this channel on YouTube although they don't post very frequently (the Bad Romance cover is better but didn't get as much alterations):
