From Brotato Wiki
Primal Dread DLC
This content is part of the Primal Dread DLC.
The DLC page on Steam is here.
To see the data at the time of the release (and before any further updates), see: Primal Dread DLC > Release Patch
Once downloaded, the DLC can be turned off in Options > Gameplay, should you wish to try the Brotato experience without it again.