Starting off, the gameplay/story balance is very similar to the base game and I personally would say the difficulty is about the same, if not a smidge harder. This a third person story and not an insertion story, which I feel allows the character's backgrounds to be deeper and more interesting.
Things I like and noticed from this hack (without going too into detail):
Overall, the story writing is hecking amazing and quite captivating: I would've already finished the game if it weren't for responsibilities. There are three special episodes, but I haven't played any of them since I am waiting to get to the break point of the main story.
Fanart is reposted on their bluesky profile, so if you have played up to the point I have, then do check it out! Some of them are included in the zip file you download, but there are some new ones that are worth checking out! Be warned, the fan art will spoil the game if you haven't completed it.
Please check this hack out if you don't mind somewhat darker themes! If I were to give this an age rating, I'd likely give it a 16+, due to some of the more darker themes.
This hack is still a work in progress, however has not been abandoned. There are updates on their Discord, and I honestly can't wait for the next part, (even though I haven't even finished this one haha).
Like the OP says, the player stays at Level 20 and there are no overworld segments, it's easy, back-to-back dungeon-ing with story in between. It's a full story-only hack which aren't the worst in my opinion: I do like myself a good story hack!
The MC talks in this hack, which wouldn't be a problem if it wasn't an insertion story, (the game asks for your name and a name to give your partner). This honestly is the only issue I have with this hack. The main reason that the MC in the base game doesn't speak often and somewhat generically, for lack of a better word, is because the MC needs to fit a wide range of people. When the MC says things that I, personally, wouldn't have said in that situation, it breaks the immersion a bit.
Despite this, that doesn't mean the story or writing is bad, far from it. I feel like it captures the feeling of the original game. It flows nicely and doesn't drag on. I was not bored while I was playing, (granted, it wasn't a long hack, but still).
Don't let my opinion discourage you! There's a reason I didn't go too into detail! Honestly, I was tempted to replay the hack after seeing all the positive feedback on it, (it has been a few months since I played through it). I personally would replay with generic species names to get that 3rd person experience I feel this game needs, however, if you want to play it as an insertion story, go for it!