This is a post-metal medley I did with my band Wyrgan of a few songs from Undertale - "Premonition," "You Idiot," and a few other motifs sprinkled in. The character dialogue (sans "Flowey") was spoken by my brother, Sam, and everything else was done by me. If you haven't played the game, the dialogue won't make much sense, but it's still kinda creepy and that's really what matters.
We did this for the MASSIVE Undertale tribute album called FALLEN by the Materia Collective. Check it out at http://www.materiacollective.com/music/fallen-undertale-tribute, there's a ton of awesome tracks on there. I did some mixing as well as performing on a few of other tracks. If you're an Undertale fan and you miss out on this, you're doing yourself a disservice.
I have my brother to thank for making this possible as well; he introduced me to Undertale, the Materia Collective, and came up with the idea/arrangement for Wyrgan.
Also, I never know whether to classify these as "video game" or "metal" under genre