>>718636340
It's a game with unique music that really stands out, great characters that have dimension despite their quirks, and it incorporates game mechanics within storytelling that few games have managed to pull off.
There's no downside to playing the free demo. If you complete the demo and then buy the game your save is carried over seamlessly.
>>718637080
This, but if Undertale turns you off then just play Deltarune. Albeit I've never known anybody who liked Deltarune but not Undertale.
>>718644471
It's a more primitive game (so you'll enjoy it more now vs. after Deltarune) but it has a good self-contained world. Many of the same characters are present across both games, but with alternate lives, and Deltarune's treatment of them is more nuanced and subtle than what you get in Undertale. Deltarune also references Undertale everywhere which you won't get if you haven't played it.
Here's a caveat of course, it comes down to taste. Some people fall in love with Undertale upon playing it and others don't, so don't worry if you don't "get it."
>>718637392
Just ignore the fanbase outside of /v/. It's a single-player game.