Deltarune is a game that honestly deserves to be WAY more popular than undertale, It's story, following a sort of narina type thing, is really well written, even some of the more jokey one tone characters, have more depth to them, for example
(spoilers are gonna be in brackets, birdley, while at first he seems like the simple nerd, ego driven person, he has a change that seems just like a joke following a small story he tells, but once you look into it deeper, he becomes much more of an actyal character instead of just a one off)
The settings of the game are also quite cool, with a second world that gets molded based on rooms from the first world, and with the game even grabbing some characters from undertale, there is so much to find even after completing the main quest. But, while the undertale call backs are cool, i find the new content even better, everything is so cool, even the smallest encounters seem like spoilers. Another amazing thing about this game is the sprite art, with undertale, everything was toned down to an agree, but deltarune really improves everything, the sprite work and animations make even the smallest things look alive, not to mention the comedy has been dialed up the LIMIT with chapter 2, while chapter 1 had small jokes every now and then, chapter 2 can seem almost like a joke at times, but it is still able to keep a serious tone when needed. It also handles the subjects of lgbtq things fairly well by just not making a big deal out of them, and treating them as a normal relationship plot or just calling the person by the pronouns without mentioning them. Overall, Deltarune's Demo is a very good play, and with and hidden fights and secret routes, it might take you a week to find everything in the demo.
Chapter 1 (7/10)
Pros
Good story and characters
fun gameplay
good sprite work
Cons
too short
all over the place
Chapter 2 (10/10)
pros
fun hidden secrets
AMAZING sprite work
fun machanics
good storytelling
CONS
none.