Undertale Yellow is a fan game for 2015’s subversive RPG sensation, Undertale. It was released in December 2023 after seven years of scrupulous development by a group calling themselves Team Undertale Yellow. Undertale’s creator, Toby Fox, was not involved in any aspect of development, but the team did receive his blessing when they first embarked on the project back in 2016. You can grab it from its Game Jolt page and start playing right now for the generous price of free.
I’ve never felt drawn to fan games, but I do love Undertale and wish I had more of it. When I heard that Undertale Yellow (made as a direct prequel to the original) released to clamorous praise from the community, it certainly piqued my interest. I’ve now finished it twice and fully intend to return to it to see the rest. Not only did the game feel like I was playing a new, legitimate entry in the Undertale franchise, but in doing so made me question my initial hesitation toward playing fan games simply because of the context of their creation.
Fan-Made with Love
It feels appropriate that Undertale would receive such a lovingly crafted and high-quality fan game. I say this not only because it has such a notoriously large and passionate fanbase but also because Undertale’s own history goes back to Toby Fox making rom hacks for Earthbound. Although Undertale immediately cemented itself in the history of RPGs with a distinct identity and reception, much of its idiosyncratic humor, visual aesthetic, and earnest flavor owes itself to Shigesato Itoi’s Mother games. The lineage of great games is one of careful iterations, and many of the best indies have one foot firmly planted in classic inspirations as the other foot steps forward into novel territory.
Then there are sequels. Due to the complex relationships between publisher licenses, development teams, and individual developers, there have been many videogame sequels in well-regarded series made by entirely different people. Final Fantasy obviously comes to mind, but those are generally standalone games, so each entry can safely have its own creative identity based on its current authoring squad.
Then we get to examples like Star Wars Knights of the Old Republic II, Xenosaga Episode II, and Baldur’s Gate III that try to build on what was put down by their predecessors with new people (or even entire companies) at the creative helms. And it’s not like this kind of thing only happens in the game industry. Following these lines of thinking, I suspect my bias against ‘fan games’ going into Undertale Yellow has been one of reductive skepticism.
It’s also interesting to think of Undertale Yellow next to Deltarune, Toby Fox’s official, partially released followup to his breakthrough phenomenon. Deltarune is a spiritual successor to Undertale, but it’s also moving in a fresh direction and carving its own path narratively and mechanically. Undertale Yellow, on the other hand, is a direct successor. It’s a prequel to Undertale’s story that concretely builds on an interesting gap in the original game’s lore.
In Undertale, six children had previously fallen into the monster-inhabited Underground before our protagonist does. You see these souls encased in glass during the game, extracted from their human bodies as a sign of the tragic fate that the otherwise kind monsters likely inflicted on them. Monsters only live in the oppressive Underground because humans banished them there after an age-old conflict. The monsters believe that harvesting the power of human souls is now their only chance to regain freedom. A different colour represents each of the heart-shaped souls you see —aside from red, that of Undertale’s PC. Undertale Yellow picks one of the other colors (hint: it’s yellow) and lets us experience that child’s journey through the Underground.
It’s a sensible move even Fox could have made following the uber success of his game. Pick a compelling part of Undertale’s iceberg of lore, flesh out the gameplay mechanics, and you have a winning prequel on your hands. Toby Fox has ostensibly moved on from the name Undertale with Deltarune—well, aside from the title being an anagram. So, it’s not too surprising that a group of talented fans pining for more time in the Underground (and we know this fanbase loves its lore) have taken the mantle for themselves. There’s a lot of Undertale fan content out there, both in writing and game mods. I haven’t engaged much with it, but everything I’ve seen that reuses Fox’s characters screams ‘fan-made’ in a way that doesn’t appeal to me.
And It Was All Yellow
Undertale Yellow is different. It’s a painstakingly genuine attempt to replicate Fox’s style without overstepping onto his creations. That’s a necessary balancing act, especially since the developers approached this project as if they were making a canonical entry into the Undertale IP. They may have gotten Fox’s blessing, but they are not Fox, and Undertale is as auteur-like of a game as you can find. If you borrow from someone else’s work too closely and don’t approach it in quality, it will come off as fan fiction. Now, I don’t mean to rip on the joys people can find in writing and reading (or developing and playing) fan fiction, but if it smells like fan fiction, it won’t taste like canon.
It’s no small achievement when I say that Undertale Yellow tastes like Undertale canon. That’s not to say that it achieves the same level of memorability, conceptual cohesion, or zeitgeist energy. But Undertale is one of the greatest RPGs of all time, so what do you expect? What Undertale Yellow brings to the table is more Undertale for fans of Undertale. More of its world. More of its addictive and smart gameplay. And it feels like Undertale—in some respects, even surpasses it. Yeah. I can’t believe I’m saying that either.
Is it the aspects that matter most? In my opinion, no. Of all Undertale’s achievements, its writing, music, and conceptual ambition stand out as its driving forces. These elements are so grounded in Toby Fox’s authorial voice that it would seem futile to emulate them. Despite this mountainous obstacle, Team Undertale Yellow give it their all. The difference in quality is palpable, but the writing and music are close enough to Fox’s standard that I could enjoy them for what they were—that is, very good. I still felt compelled to read the extensive dialogue of each minor NPC and I still bopped hard to many of the new tunes. Everything is put together with enough attention and care to the original that I was able to take it in as an authentic new Undertale game, and that’s incredible.
Team Undertale Yellow’s decision not to prominently feature most of Undertale’s main cast is an essential one. Instead, you meet a variety of quirky new monsters freshly created yet well contextualized for the existing world. Most of these characters don’t approach the original cast’s immediate appeal in look and personality, but some get impressively close. The major players here include Martlet, an earnest but incompetent rookie of the Royal Guard; Starlo, a cocky cowboy fascinated by human culture; and Ceroba, a kind and mature soul with an air of uncertainty about her. Your ol’ pal Flowey is back too, and the writers did a great job accounting for established knowledge of him while making his presence feel ambiguous again.
What’s Old is Old, but also New!
As a direct prequel, Undertale Yellow tries to balance familiarity with novelty. The beginning of the game purposely mirrors the original, and the first two areas are the same yet different. While having the player go through older, defamiliarized versions of the Ruins and Snowdin makes for some fun callbacks and extra worldbuilding, it takes a bit too long to see an entirely fresh part of the Underground.
But then you finally reach the Dunes, the third area and the first new part of the game’s world. If you look at any of Undertale Yellow’s promotional material, you notice a clear Wild West aesthetic which really kicks off here. As soon as I started running through the Dunes to the Spanish guitar strumming and Wild ARMs-esque whistle melodies of its sound palette, the game had fully won me over. Without going into any specifics, Undertale Yellow really establishes its own identity from here on out.
Even before you reach the Dunes, though, the Western theme is apparent in the design of Clover, the game’s unnamable protagonist. Sporting a cowboy outfit and revolver, Clover’s canonical character trait as the yellow soul is Justice. Clover already knows that five humans have previously gone missing after falling into the Underground. But what Clover’s intention is for pursuing their trail and fulfilling justice is up to you and takes different forms across the game’s three main routes.
Yes, just like with Undertale, the game’s structure is divided into pacifist (no kills), genocide (all kills), and neutral (in-between) playthroughs. Yet, while this structure was a hidden novelty in the original, it’s now something players will know about going in and the game reckons with that. I don’t want to spoil how it does so, other than to note that the neutral run has its own unique ending path and (incredible) final boss this time around, rather than serving as more of a stepping stone to another ending.
In battles, playing as a pacifist still requires you to use the Act command to communicate with monsters, win their favor, and spare them. The light puzzle-solving required here feels completely on par with Undertale. Then there’s the timing-based Fight command to fulfill any of your sadistic tendencies. It’s been modified to look more like shooting a gun than swinging a melee weapon, but the general premise is the same. I do enjoy the feel of the gun more, though. When you’re not selecting commands, you avoid monster attacks by controlling Clover’s yellow soul in a bullet-hell style minigame.
As a whole, the combat in Undertale Yellow is a bit more challenging than the original. Considering you should only play the game if you’ve played Undertale, it feels like a perfectly calibrated step up. If any aspect of Undertale Yellow might be a straight improvement over its predecessor, this is it. For one, each of the game’s zones has its own stylistic rendition of the original battle theme, which all sound great and help keep things fresh. Enemy attack patterns are fun to learn, and the new boss mechanics are excellent. Undertale’s boss fights stand out for their blending of narrative intrigue and personalized battle mechanics, and Undertale Yellow has no shortage of creativity on that front.
As examples, one boss has you play a Guitar Hero-like rhythm game as you engage in a dance competition, while another lassos up your soul so all movement pulls you back to the screen’s centre as you try to dodge a parade of bullets and bouncing dynamite. During my pacifist playthrough, I felt consistently challenged yet never frustrated. When the ‘punishment’ for losing a fight is that you get to experience its clever mechanics and spunky music for longer, you got a great videogame on your hands. I haven’t yet finished a genocide run, but I hear it’s very tough, as it should be. Still, if difficulty isn’t your thing, there is an easy mode on offer.
If there’s one main critique I’d raise against Undertale Yellow, it’s that it turns what felt like a magic trick in Undertale into routine. This isn’t a fault of the game’s execution but a natural consequence of creating a direct, faithful successor to such an original vision. When it first released, Undertale was bursting at the seams with subversive novelty, buried secrets, and meta brilliance, making it a standout gaming experience and a darling rabbit hole for lore diggers. By simply giving us more—however well put together—Undertale Yellow can’t aspire to be much more than a good followup. For almost any other series, this could hardly even be considered a criticism; Undertale is an exception.
Return to the Underground
Undertale Yellow doesn’t seek to use the legacy of its namesake to take a daring new step in the history of RPGs the way the original did, but it does take a significant step in the history of Undertale. It’s a lovingly crafted addition to this universe served up to a fanbase salivating for more. With that said, I noticed that it’s created a rupture in the community between Toby Fox purists who reject it as an attempt at canon and those who accept it wholeheartedly as a worthy and respectful effort to expand on the product that inspired it.
I might have sided closer to the former group had I not trusted the positive reception I saw and gave it a shot. I’ve been semi-patiently awaiting the full release of Deltarune after devouring its first two chapters, and Undertale Yellow has done an impressive job filling that hype-induced void. And I’m not even done with it! To call it a side dish for Deltarune would be a disservice, as this is a satisfying three-course meal in itself. It may not hit the same highs as Fox’s work conceptually, but as a charming, well-designed return to the Underground, it’s a remarkably confident and compelling release.
