Yoshiro Kimura, creator of the game "Moon: Remix RPG", said that playing Undertale gave him the courage needed to make his new game, "Stray Children".

Inside the Fangamer Tenna plush is a pipis.

On July 3, 2015 Toby uploaded a file called 67.wav to his website.

The Danganronpa fangame "Project: Eden's Garden" released some art for Halloween, in it the character Cassidy is seen dressing up as Tenna.

In the Japanese version of Undertale, Mettaton's "Game Show" is instead a "Quiz Show".

In the intro of Chapter 3, if you move right until the couch is off-screen, it will start walking.

In a leaked episode of "My Little Pony: Tell Your Tale" titled "Digital Detox", you can hear the Undertale song "Home" in the background during one of the scenes.

Yesterday Toby fox accidentally retweeted Deltarune fanart on his main account and immediately undid it.

In the Holiday House during the weird route, if you go down to the basement instead of Noelle's room, you find Susie searching around. If you wait long enough she has a few lines of dialogue.

In the Steam page for the Deltarune game + Soundtrack bundle, there is a small gag in the copyright section.

In the 10th anniversary stream, Toby references this, as well as we get to see this feature in game.

During the Undertale 10th anniversary stream, Toby reveals that "Nyeh Heh Heh" was originally Lancer's theme song. He calls this information "famous" despite having never shared it before.

For a short time in 2010, Toby Fox was a radio host for Skaianet Radio, a fan-operated live online radio for Homestuck music.

After defeating Tenna, when he flickers through channels at the end, the last channel number before it turns off is 66.

There was a time where Toby would play Hopes and Dreams on the piano nearly every day, however due to his wrist pain he couldn't play the piano for long so he had to stop.

If you compliment Lancer three times during his fight and get hit, the damage counter will appear sideways.

In the Japanese translation of Undertale, the line "Can I Speak to G..." is purposefully left in English, because if written in Japanese it would reveal more information about the identity of "G".

Inside the code for the Susiezilla minigame, there exists a variable named "cliffordthebigreddogisakaiju". It is set to true and is never used again.

Toby Fox accepted an award on-stage in 2015 for Undertale. At the Fun & Serious Game Festival in Spain, Undertale won Best Debut Game.

Near the end of each Chapter there is a way to tell if you have recruited every enemy or not. Trashy in Chapter 2 which only appears if you haven't recruited everyone, the employee list in Chapter 3, and the judgment bell in Chapter 4.

Due to Muffet being so difficult originally, sometimes kids would email Toby saying they couldn't beat her, so Toby beat Muffet for them and sent their save file back.

Japanese composer Nobuo Uematsu shared a picture of himself with Toby fox yesterday.

During the Tenna fight, the check text can change if certain conditions are met, it changes if you have the Dealmaker equipped on any party member, or if you have completed the Sword Route. If both are met the Sword Route takes priority.

In the files for Chapter 3, there is an unused portrait sprite of Elnina. Oddly this sprite is labeled under Lanino's name, despite depicting Elnina. It is also notably weird due to being black and white, even though Darkner portraits use color.

When you play the racing game in the Green Room you can't normally see what is happening. However the game is actually playable, and if you change the variable "_debug_visible" to true, it allows you to see the game.

In 2022, Toby fox collaborated with "Pocari Sweat", a Japanese sports drink, and did the music for a commercial. Originally, the company wanted to use "Hopes and Dreams", but Toby declined and offered to make an original song instead.

Due to his hand and wrist pain, Toby doesn't actually program anything anymore, and instead has his team do it for him. However sometimes he will get on call with one of them to tell them exactly what to do. (Picture from Debug Magazine issue 10)

Today is Toby's birthday! Also, earlier Masahiro Sakurai shared a picture of himself with the judges of the Japan Game Award's "Game Designers Award" which includes Toby Fox.

Toby once did a Let's Play of Earthbound on the Starmen forums in 2007, Which can still be accessed via the Internet Archive.

When fighting the two Guei enemies in the Dark Sanctuary, if you use the OldMan ACT twice, the Old Man will recruit them and you can find them in his study.

The Deltarune song "And Now For Today's Sponsors...!" is named "baci_perugina" in the files, which is a reference to the Italian chocolate brand Baci Perugina, which always contains a love note in the wrapping.

In Mettaton's alarm clock dialogue, his line "So we decided to settle things as responsible adults." has alt text reading "So we decided to settle things, ahem, humanely." which is notably different from what he actually says in the image.

Asgore's golden armor was inspired by Amon from Lufia 2.

The Monstercat x Undertale album made for the 10th anniversary is releasing tomorrow.

Two of the answers for Mettaton's 3rd quiz come from the classic nursery rhyme "What Are Little Boys Made Of?"

WayneradioTV, who plays Spamton A Spamton in the Spamton Sweepstakes and Undertale 10th Anniversary livestream, received a special custom Spamton plushie from fangamer depicting him as Spamton.

Asriel says "Jafe" whenever he strikes with Chaos Sabers in his boss fight, but it's hard to hear because of how quiet it is. (Music removed to make it easier to hear)

In the Homestuck Animated Pilot, a framed picture of Andrew Hussie and the Annoying Dog standing side by side can be seen in Hussie's room for a single frame.

The track "Dog hole" first appeared in a tumblr post on the Undertale account in 2016, and showed up once again during the Undertale 6th anniversary stream, before finally being used in game for the dog hole area in the Undertale 10th anniversary stream.

Toby Fox was originally a composer for the game Starbound. Alongside an early version of "Snowy" from Undertale, there are three other unused songs in the code that likely also belong to him, as they are made with his commonly used soundfonts and VSTs.

In the Homestuck animated pilot, John Egbert, the character that Toby "Radiation" Fox voices swears quite a lot, totaling 17 swears in 11 minutes.

The Undertale 10th anniversary development team gave the Spriters Resource Team the new sprites that appeared on stream.

Undertale version 0.99.5, a prerelease build of the game from just a week before release, got found recently. The changes are small, mostly items descriptions, small dialogue differences, and a few internal differences. But you can see the full list of changes in the replies.

In the files of Deltarune Chapter 4, there is a unused texture named "spr_rotating_tower_fg_stone2" which is just the texture of Stone Bricks from Minecraft.

Toby made a post on his tumblr about a sub-melody in ASGORE being hard to hear in the final version.

The names Napstablook and Asgore were both randomly generated.

During the Undertale 10th anniversary stream, Toby once again refers to the form Flowey takes after absorbing the souls as "Omega Flowey"

In Undertale, there is a variable named "donkeykongismyfavoritemarvelsuperhero", which was directly referenced during the Wrong Number Song on the Undertale 10th anniversary stream.

Inside the code of the unused stable in Undertale, there is a variable called bibblybeebly set to 349382 which is never used in the code again.

Toby Fox will be a judge for the "Game Designers Award" at the Japan Game Awards 2025.