"CORE - Undertale" is a high quality rip of the song "CORE" from the game Undertale.
The rip starts with the melody of The Nutshack theme played by the instruments of "CORE".
Then, it's a mashup between The Nutshack theme (dubbed by the original instruments) and the advertised track. In the background, the song "Window Licker" by Aphex Twin can be heard faintly.
- The rip description lists the platform as "NS", probably as a reference to the joke used.
- The Nutshack intro used in this rip is actually SiIvaGunner's version from the second ARG. The Flintstones theme can be heard at 1:01 and 1:29.