This is the greatest game of all time. Seriously, I can think of no other game that matches this. The story is fantastic, with a very deep lore and one of my favorite plot twists in video game history. The soundtrack is of course amazing, with frantic, adrenaline inducing tracks like MEGALOVANIA and Spear of Justice coupled with quiet, more reflective instrumentals like Memory and An Ending. I love fourth wall breaking, and UNDERTALE does this a lot. The writing and jokes are top notch, I laughed out loud too may times to count. All of these things are fantastic, but I have not talked about the two best aspects yet: The morality system and the characters. You see, in UNDERTALE, you have the choice as to whether or not you want to kill or befriend the monsters you come across. Other games use morality systems too, but UNDERTALE makes it so that your choices have real impact for the rest of your playthrough, and people will not forget the fact that you murdered someone just because you complimented some random guy. Your actions have weight. The characters are just... amazing. Each of them exude a huge amount of personality and charm, even the one-off minor ones. They all have their own motivations and feelings and all of them are sympathetic and likeable.
In conclusion, all of these elements (story, soundtrack, humor, actual weight to your actions, and AMAZING characters) create what I consider to be the greatest came of all time. There are no problems with it whatsoever.
None.
None at all.
It's not like it has a toxic fandom or anything like that *cough*.
I give UNDERTALE a 10/10.