https://www.gamespot.com/reviews/undertale-review-nintendo-switch-update/1900-6416315/

Editor's note: Three years after its initial release on PC, Undertale has found its way to the Nintendo Switch--and of course, the game is every bit as charming, challenging, and harrowing as it was the first time around. Undertale may seem like a straightforward retro-style RPG, but it subverts player expectations every chance it gets, which never gets stale because of clever writing and an evocative chiptune soundtrack. Thankfully, it plays just as well as it does on other platforms without any performance hitches or bugs after putting about hours into this version. Like its console counterparts, you can fill the screen with an adaptive border that thematically fits with the location you're in (Undertale plays in a 4:3 aspect ratio). Dodging enemy attacks in the bullet hell-style defensive phase in combat works just as well with the Joy-Con analog sticks.

Undertale isn't afraid to break convention, and because it does so in a way that's thoughtful and humorous throughout, the result is an emotional rollercoaster that fills us with determination. -- Michael Higham, 14 September 2018 [We have updated the score to reflect our experience with the Nintendo Switch version, in addition to the PC, Mac, and PS4 versions. The original review follows below.]