"Robert F. Fox (born October 11, 1991), known professionally as Toby Fox (previously Toby "Radiation" Fox), is an American video game developer and video game composer. He is known for developing the role-playing video games Undertale and Deltarune for which the former garnered acclaim and he received nominations for a British Academy Game Award and three Game Awards.
Fox's early work consisted primarily of composing music, notably doing so for the webcomic Homestuck, and, following the success of Undertale, he went on to compose music for a number of other independent video games. Other notable works include contributing to the soundtracks of Super Smash Bros. Ultimate and two Pokémon video games."
-Wikipedia
Undartale was his first video game that exploaded with popularity and sucsession. The main character is a child that had climed Mount Ebbit and fallen into the underground, a place where the humans banushed the monsters.
"In this RPG, you don't have to kill anyone. Each enemy can be "defeated" nonviolently.
Dance with a slime. Pet a dog. Whisper your favorite secret to a knight. Or, ignore this choice and rain destruction upon your foes.
But your journey will take determination. Each adversary has unique bullet patterns that you must dodge as well.
Emphasis on humor, character dialogue, and player choice."
-A section from Undertales About Page.
Deltarune, as Toby Fox exclamed, was created from dreams he had. The main character is a human kid who lives in a town of monsters, and soon learns of another world they are ment to save, or posably distroy.
Other chaptors are eagerly awaited, as there is said to be 5 chaptors to this game. Some fans theorise however, that there will be even more.
"UNDERTALE's parallel story, DELTARUNE. Meet new and old characters in a tale that steps closer to its end, chapter by chapter. Dodge bullets in nonviolent RPG battles as you listen to funky, funky music. Try Chapter 1 and 2 for free... now!!! More chapters in development!!!"
-Discription from Deltarunes Steam Profile.
Lets not forget Homestuck. Toby Fox allong with many other artists worked on music and audio for the webcomic Homestuck. Fans may know or recognise that some of his work from Homestuck sound familiar to and/or are early verions of Undertale songs know today. Like Homestucks MeGaLoVania sounding like a young, guitar version of one of Undertales most famous songs Megalovania.
Pokemon songs in SWSH and SCVI.
Earthbound Halloween Hack.