psy10

I don't know about Monster Hunter, but Bloodborne has an archaic language even in English (although in English we can handle that relatively easily), and you will end up looking up words a lot if you want to understand the lore/story which is conveyed 95% though item's descriptions (Which is a cool way of conveying a story, but archaic language... not so cool!)
Xenoblade is not bad at all, I'd say it falls in the range of easy to moderate, but it's all relative to other games I've tried to play of course (don't forget Fatal Frame, I should've mentioned Resident Evil as well).
I'm still a bit afraid of getting a N3DS and finding out the kanji is too blurry, I bought a ps1 with some games in Super Potato when I was visiting Japan, and boy do my eyes hurt from trying to read it.

Very nice on having a girlfriend who shares your interests! Is she Japanese? Did you get to know her by chance? I don't think most Japanese women, even if they like video games, would be openly admitting that in public (correct me if I'm wrong).

I never took a class in Japanese, however I made myself a structured method, like the one I outlined, so it works out.
Regarding motivation? That's easy just forbid yourself from playing video games if not in Japanese ever again (unless a special game comes a long once every few years like Pillars of Eternity), you will be motivated because you want to keep playing video games like you used to but you have to get better!
Not only that, assuming you need a vocabulary of size X to manage games fairly well, you will be highly motivated to reach that number as fast as possible, and that will only be achieved through playing more and stumbling upon unknown words! Found an unknown word? YES! LEVEL UP! (an exaggeration to illustrate a point of course).

I'm in the exact same boat as you regarding the method of studying.

I started about 2.5 years ago, right after studying the most common 1000 words and basic grammar I jumped into playing.

The method was (at least most of the time) to go through the game, and checking each and every unknown word, if it contains kanji, I also learn that on the way, and add the word to a list, which by the end of the day was added to Anki.

I started with persona 4, the dialog at the beginning where they ask you to choose a difficulty and explaining what type of difficulty is suitable for different kinds of people took me more than 30 minutes to go though! Each kanji was new, each one had unknkown radicals, I used RTK and kanji.koohii.com for the stories, and made mnemonics for the reading. Saying it was a rough start is an understatement.

I also watched anime with japanese subtitles (with pausing a lot) and did the same thing.
My first anime that I watched that way was FMA brotherhood, the first episode took me 4 days.
By the time I got to the last 4 episodes, I got to a level where I watched them in a single day!

The philosophy is basically, once I stumble upon an unknown word, it's mine. Next time I'll see it I would've already known it.

I've been doing this with breaks, so I would say 2.5 years - 0.75 years = 1.75 years.
My deck size that's made up solely of words learned through this way is 10,000 (I have another deck of just common words regardless if I saw them in games/anime).
That's an average of ~15 new words a day.
Of course some days I would barely stumble upon a new word! (depending on the game type), while I had days with up to 100 new words in a single day!!

This method still goes on to this day, however now that I know better I sometimes understand words from context good enough that I skip adding them to Anki, or I stumble upon a word that seems so archaic that I skip it as well.

I just finished Bloodborne this week, needless to say I learned a multitude of words that a Japanese friend i'm corresponding with have never seen in his life! For example: 穢れ.
I've yet to finish a single traditional JRPG in Japanese. I stopped Persona 4 after about 20% of the way as I wanted to try playing other games.

Played quite a bit of Fatal Frame, a lot of Vita/PS4 games (not finishing them), especially those you get to play for free every month from ps+.
Unfortunately I'm not yet at the level where I can play a JRPG from start to finish in a short enough duration that I won't get bored of it before it ends.

I'm contemplating between Dangan Ronpa, Xenoblade and Tactics Ogre for my next game. For now I'm trying Xenoblade.

This post turned out longer than I thought!
Anyways, just wanted to say I would be glad to join such a community!
Please let me know if you establish or find one.