No one knew for sure what it would be, but it turns out that it’s a fully playable game! Yesterday, the Undertale Twitter account cryptically teased the release of something big today. Download the game free HERE from the official site. However, it now seems that Delta Rune is its own full game. The new Undertale spin-off, Delta Rune, was released today, and many interpreted it to be a short teaser for an upcoming game. Turns out that the new game release by Toby Fox, the creator of Undertale, wasn’t just a teaser for an Undertale sequel, but a full game entirely.