Undertale-Deltarune
Undertale, along with Splatoon was a cornerstone of my media diet as I really started becoming a artist and writer, and Deltarune a few years later came out at just the perfect time to satisfy my reminiscence on it. But tragically, I'd fallen out of the loop of the series until 2025! Just before the 3rd and 4th chapters came out, prompting me to get back into it, and Jesus H. Christ did I get back into it!
Deltarune quickly skyrocketed to GOTY and maybe even Game of the Century status for me, and while I haven't replayed Undertale in full yet, I have only grown more appreciative of how Toby Fox's writing so clearly rubbed off on me back then. The characters, the themes, the HUMOR -- it is all so perfect and Toby Fox's work has quickly become a pillar of my life again.
Overview:
Fave Chapters:
Being that there's only two games present, I've decided to focus on ranking the available chapters of Deltarune (which I place above Undertale easily I fear).
1. Chapter 3
A massive upset for those fallen prey to recency bias (JK), but Chapter 3 is without a single doubt my favorite chapter so far and I do not feel like that will change anytime soon. No matter how epic the rest of the series gets I don't think anything will top the raw emotional nuclear bomb that this chapter and its themes mean to me.
2. Chapter 4
4 is by far the best chapter yet, mostly in terms of narrative and grandiosity compared to its more flashy younger sister chapter. Susie, Kris, and Ralsei were all elevated to new heights of development and so much about the central mystery was put forth for us to untangle for years. 3 and 4 compliment each other very deeply and if not for my bleeding heart this would be the logical trump.
3. Chapter 2
The impact this chapter had on the fandom and internet at large was something I was only periphery to for those 4 years between it and the 3 + 4 drop, but that impact was loud and clear. Playing it basically as my reintroduction it instantly enraptured me far more than the first chapter did back in 2018, and I always think about how I wish I had more time with it.
4. Chapter 1
I have a lot of fondness for the first chapter, as it wasn't till just before 3 and 4 came out that I played the 2nd, so really THIS was my memory of Deltarune for those 7 years. Despite that it is inarguably weak and clunky on its own compared to its successors, which is not a bad thing as an introduction.
Fave Characters:
It is really, really hard to overstate just how legendary of a character writer Toby Fox is as well as how much of an impact his characters have had on me -- from defining my style of writing in Undertale to derailing my life with conspiracies in Deltarune. So of course both games need their own spotlight
Undertale

1. Flowey
I don't think any character has stuck around in my mind from the game quite like Flowey. From cheap but memorable early subversion, to his transformation into an elderitch player-critique deity, to his pacification into Asriel, this motherfucker holds a LOT for the game and I am always delighted to see his stupid face. Another cute but duplicitous little cunt for the pile (next to some Kirby faves).

2. Toriel
Picking her feels kinda basic and like a bit of a self-report that I have not replayed much but the beginning of this game in years, but Toriel is once again a character who has always been with me. Her presence genuinely comforted me when I was younger, and with more distance I also think she does serve as a great introduction into the moral framework of Undertale right after Flowey.

3. Alphys
I always loved Alphys as a weird, sweaty, fat, weeaboo girl character, and that has honestly not changed with age as I still find her character really unique and endearing. As in she represents a lot of unpalatable tropes usually tossed at men but gets to encompass them in all her silly, bisexual glory. I could never be mad at her, no matter how many unethical experiments she committed or how terrible a teacher she is.
Deltarune

1. Tenna & Spamton
I had to put them together because it would feel so unfair to have them one after another, they take up an unreasonable amount of my love for Deltarune. And this is not an uncommon sentiment, both of them are masterfully interwoven into the core themes of the narrative while also being very fun as sideplots, and of course even better together. Spamtenna Doomed Yaoi, Spamtenna Divorce -- it's all a vain attempt to capture the absolutely atomic levels of chemistry these two have together and I live for it.

2. Kris
Before Chapter 4, I would say that Cloud Strife was probably my favorite protagonist in everything ever, and especially in tandem with his dynamic with Sephiroth. But now, Cloud has been deposed, because there is another not-so-self-insert protagonist who's arc completely throws player agency on its head and they are bigger and better and more mentally ill than ever: Kris Dreemur Deltarune! I love this little fucking THING of a protagonist and all of their never-ending hatred for me as their controller, war and hatred on planet earth.

3. Susie
Susie has been with me since my first year out of middle school and I remember being very fond of her then, and now I wish so much that I had what we've seen of her character back then. She is the most delightful and delectable mean weird girl character and she reminds me so startlingly of myself and how I found my strongest bonds in the real world through expression of my bonds to fiction. She is the light of everything.
Fave Boss Fights:
Undertale

1. Omega Flowey/Your Best Nightmare
As I said, Flowey is absolutely iconic and the part that truly cemented that was this bossfight. It is also of course where the game most aggressively pulls out all of its tricks with its metanarrative fuckery on save files and the entire thing is still one of my favorite twists in a game ever. Helps of course that the accompanying track slaps such fucking ass, fucking mwah, chef's kiss for insanity.

2. Undyne the Undying/Battle Against a True Hero
I did attempt a genocide route back in the day, on a bootlegged copy of the game running off a harddrive on my school computer I only played during the middle school lunch periods. Unsurprisingly, the entire experience was emotionally grueling, but the role that Undyne plays as your first wall, and the one that broke me, always felt profound. I guess for my world she did become a real hero and save what was left of The Underground.

3. Toriel/Heartache
Once again, everything about Toriel is such a perfect introduction to the game, and despite EVERYTHING thinking back on this fight still breaks my heart, whether its pacifist or violent. I've always loved too how the song itself opens up from a more flat chip-tune production to a fuller suite of samples that perfectly parallels how this fight is the key to opening the rest of the game in plot and themes.
Deltarune

1. Jevil/The World Revolving
Call it Stockholm Syndrone as this is probably the hardest secret boss in the game (outside of the Spamton solo rematch in Snowgrave but that feels unfair to how easy he is otherwise), and THE MOST FUN! I love the energy, and Jevil is literally just such a treat to rematch that it almost makes up for how little love he gets in comparison to his mailman upstart.

2. Tenna/It's TV Time!
God still the most exhilarating and creative of the Final Bosses so far. It helps that I love everything about Tenna, but its also that his presence in the story really helps build up to this fight and makes it feel like a true culmination of not just the plot but his huge character arc. Never before has a theme so perfectly captured the sound of an entertainer breaking down on air.

3. ERAM/Burning Eyes
This one of the few bosses where the song isn't super integral to me, but the build up to ERAM is probably some of the best since Spamton and captures this creepypasta flavor the game is diving into so well. I also just love this mysterious, almost nothing-burger bitch of a character and how this fight throws the gameplay completely on its head for such a unique challenge. John Mantel
Fave Songs:
Yeah, yeah, we all know Toby Fox is a masterful composer who perfectly interweaves textual and musical storytelling, I shouldn't have to tell you. I'm mostly going off personal sentimental value rather than the raw quality or epicness of the songs. There will be many honorable mentions, and Deltarune gets 5 whole songs cause its so fucking BIG.
Undertale

1. Another Medium
Though it nor Hotland ever meant much to me back in the day, they've both been sticking in my head more as time goes by. I think something in me is just starting to really connect to how amazing of a penultimate setpiece all of Hotland was. It's also just a super majestic song.

2. Fallen Down
This was my immediate fave and I have very fond memories of using it as a lullaby for myself when I had bouts of insomnia as a kid. The ruins are known to be kind of boring to most but I wanted to live in them so bad when I was younger, Toriel's presence and the closed in space was just so comforting in that chilling place-stuck-in-time way.

3. Here We Are
The True Lab is one of the best parts of the fucking game, the heel turn into horror, and ATMOSPHERIC horror instead of just the chaos of Omega Flowey was handled so well and it stuck with me for so long. This song was also probably my first real introduction to this kind of moody music that I've come to love in games like SH2 or Tekken.
Honorable Mentions:
Uwa! So Temperate, Waterfall, Undyne/Run!, Chill, Hotel/Can You Really Call This A Hotel, Core, Song That Might Play When You Fight Sans
Deltarune
1. Paradise, Paradise

This song is so good it should be illegal. All of Chapter 3 felt like a personal attack on me, but this track in particular is trained directly on my heart. I fucking hear you Toby using the Ishikawa synth in Sandy Board and now bringing out this KDL3-ass composition for hanging out with Tenna and breaking his game, adding a sickeningly bittersweet twist to the notion of an escapist paradise!
2. BIG SHOT

Yeah I... It's peak. This entire fight and everything about Spamton is peak. It's not a more fun fight than Jevil mechanically, but the music and the build up and all of it just works PERFECTLY. God the names of the Spamton tracks even complete each other... We as a society are literally never going to recover from the sheer impact of Spamton and Big Shot.
3. The Roaring Knight/Black Knife

This fight and the theme chilled me to the fucking bone. My favorite thing is that unlike so many other themes, I love the feeling that it's not COMPLETE yet. Not that the composition is physically unfinished but emotionally, it has so many motifs I just KNOW will get thrown on their head as the story progresses and it makes me so excited! Perfect fucking mid-story boss.
4. Third Sanctuary

I absolutely have to give it to Chapter 4 for being the best in terms of scope, even if my broken autistic heart is most attached to Chapter 3, and I think the way the overworld motif evolves across the chapter perfectly encapsulates just how GOOD.
I can't help but think of Susie and her ever-growing passion for her role, the way she finds purpose now so strong in these endless nights running around dark worlds with her new friends, confident enough to deny fate and probably suffering from delirium. It's different chills from Chapter 3, but it gives them all the same.
5. Vapor Buster

Rude Buster was a show-stopper the second it hit the scene and I love it dearly, but this remix - even more than Ruder Buster - just scratches such an itch. Somehow it brings me back to how the original FELT -- this dark, kickass, twisty version. I'm kind of sad it might be more of a gag composition.
Honorable Mentions:
ANOTHER HIM (PS2 menu ah music <3), The Legend, VS. Susie, Girl Next Door/Ferris Wheel, Smart Race, WELCOME TO THE CITY[Snowgrave], Acid Tunnel of Love, Sandy Board, Glowing Snow (My GOAT Uwa! is back!), TV WORLD, SWORD, Ripple (literally the best), SPAWN, The Place Where it Rained, Airwaves (reminds me of music I used to listen to back in 2015 + Spamtenna anthem)
Fave Trivia (& Mysteries):
It's hard to come up with interesting and specific fun facts about Toby Fox's games when it's always been in their nature to be picked apart to hell and back, so I'll focus on things I have some personal connection to or I feel informs a character really well.
So Sorry Controversy

Yes, I was there, and in case you weren't: Undertale has a secret boss named So Sorry who was an insert by an OG kickstarter backer, which gained a looot of controversy because the backer in question was a fat-fetish furry and their insert was their own sona. It was some classic knee-jerk furry-phobia made all the more surreal by my oblivious 11 year old self being a follower of the artist without context that their art was so loaded. In recent years I've heard the artist has been up to nasty stuff, but it doesn't stop the initial backlash from just being pure fear-mongering.
Whatever Is Going on With Chara

Despite everything that has been cracked or at least heavily theorized on to the point of taking shape as a coherent thesis in my head, nothing has remained as much a mystery of Undertale as Chara. I blame this on having the concept confused for me on contact, as like every dumb child I assumed first thing Chara was The Evil Entity Who Caused The Genocide Route!, but I had a friend who was incredibly adamant to their innocence. But I can't remember their explanation.
Recently my fixation on Undertale as narrative focused on player action has drawn me back to that conclusion, but it still makes that child such a mess. I appreciate that Kris seems to be a complete reworking of whatever they meant to get across in the story.
The Spamtenna Divorce Iceberg

So the fact that Tenna and Spamton were once business partners of dubious intimacy and their falling out left them both in wrathful shambles is not much of a secret to even a casual player of the main plot, but its really the deep cuts that sell everything and drive me insane.
The fact that Pipis make absolutely no sense and may or may not have massive lore implications but as of Chapter 3 they seem to represent fake children between the two. The fact I had to argue with my friends whether "Cungadero" or "Cowabunga-dero" - two complete stupid nonsense phrases - came first between the two! Mike being some sort of shared hallucination between the two! THE LIETMOTIF BEING TAKEN IN THE DIVORCE!! It's all so much and is so stupid and I am so obsessed.
Kris Facing The Player After Dialogue

As stated, the antagonism between the player and Kris is one of my favorite things ever, and I love how the magnitude of Kris' rebelliousness started small but progressed across the chapters. Into Chapter 4 I was questioning and cursing nearly everything Kris did, and even looking back before there were so many little moments that make me howl in disbelief. But the one that has driven me the most paranoid is the fact that Kris turns to face the screen after any dialogue has passed. One would think it only a slight quirk of the game at first, but now everytime that blue bitch turns to me I scowl the fuck back in absolute suspicion. This little krunt.
What Is Ralsei?

The broader discussion of what light world object Ralsei represents - knife, headband, shadow, Asriel's ashes (stupid???) - is of overlooked significance in my eyes. I think it's meaning means the most to me as someone super enraptured by the meta physics of the dark world as more a figment of imagination than most theorists seem to give credit, and understanding what Ralsei is will probably be a huge piece of the puzzle of understanding that dynamic.
I would also just like to give a shoutout to my friends and I who genuinely got together and decided Ralsei was Kris' pocket lint for a moment.
Friend Inside Me & The Mikes

YOU KNOW WHAT'S FUCKING HILARIOUS? I was there, but only for like the last couple weeks. Remember -- I caught up with Deltarune right in time for Chapter 3 + 4, so I almost MISSED Friend Inside Me but got suckered in right before it got completely laughed out the room.
FR though? I'm actually still proud of that fandom theory, it was bonkers but in a way that was very much picking up what Toby was putting down in thematic and humor senses. If you missed it -- basically people suspected Chapter 3's secret boss would be a Woody Toy Story like because of references to a cut cowboy section and old shitpost remixes of the Friend Inside Me Song on Toby's tumblr.
But of course, to pay respects to us clowns, we did get the Spamtenna collective hallucination sidekick(s) - the Mike polycule - out of it all, probably the best troll of all time.