Undertale is a game that lots of people like to discuss to the point of obsession. It seems like one of those quirky, overhyped games that doesn't turn out to be nearly as impressive as you've heard from the rabid fan base. It's not technically impressive, it's not even artistically great. Of course, art is subjective but that's just my opinion. It doesn't have online play or a 80+ hour run time or a budget of 100 buttzillion dollars. After having played through the game twice, I think the praise is well earned.
What Undertale does have is great characters and a hell of a lot of heart. I'm not usually the kind of person to care about that kind of thing. I like Bloodborne. I like Fallout 4. I like Cities Skylines. I don't usually play games for "feels" but I definitely got it from Undertale. I'm sitting here at almost 2 am with dried tears on my face. I just finished Undertale for the second time in order to get the true pacifist ending. After this I had originally planned on going through the game again to do a "genocide run" where you kill everyone. I definitely won't be doing that anymore. I can't.
I genuinely care about Undertale. I care about the characters and am happy to have had the opportunity to play through such a charming, unique game that gave me feelings that video games rarely are able to do. I'll never forget Undertale and I hope you decide give it a chance. I think you might love it as much as I do.