Oh boy! An excuse to talk too much about Undertale!
For me, what really makes Undertale sing is its strong understanding of the language of videogames; its ability to bring together mechanics, writing, and music to make dramatically (and often comedically) powerful moments
The biggest (but not only) example is the how combat works. Normal battles aren’t just fights, they’re little character vignettes, expressed through both writing and systems. These are often funny, but they can be sad or creepy, too. And instead of the traditional “boss fight then cutscene” model of storytelling most games in the genre opt for, Undertale frequently brings those elements together to make stronger, more singular moments.
Early game spoilers: By the end of the Papyrus fight, you’ll have either convinced him to be your friend, or you’ll have killed him. In either situation, the mechanical tension and the narrative tension are ultimately the same thing and are resolved in unison. The sequence would be far weaker if it was just a fight where you beat him up for a while and then afterwards you got a narrative scene where you make a moral choice.
It’s a part of the game that I rarely see talked about in depth, but I genuinely believe that it’s an incredibly important part of why Undertale was so affecting for so many people.
(Also, Hollow Knight is extremely dope, and would definitely be in my top 3 games of 2018 if I hadn’t played it in in 2017)