Characters who grow cynical and jaded by the time of Undertale are instead still friendly and legitimately helpful in this prequel. This gives a ton of different takes on established characters. The story of this game is a prequel to the original Undertale. To install Undertale Yellow, simply run the installer and you're good to go. Well, history seems to be repeating itself, with a creator approved Undertale Yellow releasing its demo. And even back then, it definitely had all the features that made it insanely popular when it did finally come out - it had the same quirky humor, great music, and heartrending decisions. Before Undertale was released, it had a demo that it distributed to a ton of different streamers and influencers to get attention.