The writing in Undertale is largely excellent. The humour is fluffy, endearing, and consistently funny, and has a habit of aggressively fluctuating between being intentionally predictable and wildly expectation-defying in a manner where each side of that ends up complimenting the other. The characterisations are striking and memorable, but even more than that the game was so effective at making me become attached to these strange monsters; I was genuinely sad having to leave Toriel's side at the end of the first part of the game due to this attachment that had rapidly formed, and on the other side of the equation many of the other main characters felt like friends by the game's end. This is particularly impressive considering you don't actually spend that much time with any individual one due to always travelling alone; so many rpgs will have multiple people travelling with you in your party and yet have none of them feel like friends by the game's end, whereas Undertale is able to take these characters, some of which are initially threatening or even actively scary, and make you fall in love with them wanting to spend so much longer in this world in their company than the game gives you. The majority of the plot is also just very enjoyable, falling into the same space of mixing the dangerous and dark with the cozy and comfortable in a way where both elements are able to compliment each other well; this is going to sound really weird, as they're very different pieces of media, but the feel of the adventure you go on reminded me of the feeling of curling up in bed, late at night, at 9 years old, reading The Hobbit by lamp-light.

And then there's the ending(s), where I found the writing much less unreservedly wonderful, both disappointing and honestly contextually kind of confounding. The moment where Flowey just took over at the end of the Neutral run, shutting down the game and then engaging me an aesthetically clashing fight alongside oodles of meta nonsense...at absolute best soured the experience for me. I am very okay with meta elements in games, and I'm very okay with games doing what this ending tries to accomplish, in fact that's even exciting space that I'd love to see explored more, but here it just felt so out of place. Out of place both in terms of the text, where only a scant few references, most very early on in the game, make you think anything meta could be going to happen, and certainly not to this ever-so-extreme extent, and in terms of tone where again it just feels so dissonant with everything that led to this point. I love seeing this sort of territory explored typically, but here it just felt like it didn't fit and my emotional response was such that I felt robbed of an actual ending. The True Pacifist ending goes some way towards fixing this, with a more satisfying ending in some regards, but it gets bogged down in this mass of plot twists and sudden, unnecessary developments that led to me partially not entirely following what was going on and partially just baffled at why we ended up at this point.

Outside of the writing the battle system feels completely unique, taking all the best parts of bullet-hell and JRPG battle systems, throwing the less appealing elements of these genres to the side (the exhaustion of bullet-hells, the sinking into repetitiveness of JRPG combat), and uses this as a way to both create humour and also allow the world and monsters around you to express themselves. The soundtrack really lives up to all the praise too, at its peak stirring and emphasising the emotional chords the game is so good at hitting (the music upon entering New Home is my favourite moment of this, perfectly bringing out the feeling of nostalgia, this mix of melancholy and fond-memories, this feeling that you're at once both back among those times you came from and cherish and yet can in reality never truly return). The music is so good that even as I found myself frustrated with the mess of details tossed around in the True Pacifist run ending I still found myself getting caught up in the emotions of the final battle regardless.

I love Undertale, but also don't know that I will ever work through these deep frustrations with the two endings I played through, especially so with the Neutral ending. There are moments here I'm going to treasure and carry with me for a while, but these endings clash so badly for me, feel so out of place, that I don't know that I can ever truly return to this game knowing how much they upset me. I hold a lot of this game in high regard, but am also to some extent left on some level feeling mixed, unsure, frustrated.

UPDATE: This world and its characters have grown on me more and more since playing, and I think even the endings I have grown to appreciate more over time. Now just soundly in love with the game with very little in the way of reservation.