From publisher blurb:
The Valley Out of Time is a series of ‘zine-sized adventures from SGP. This valley can be placed in any ongoing campaign, and is set in the “Neanderthal Period” of development. Huge monsters – both dinosaurs and otherwise – and devolved humanoids plague the area, and only the hardiest of adventurers will prevail! This series of adventures borrows heavily from classic dinosaur art, books, and movies; if you’ve ever seen a classic Frank Frazetta or Roy Krenkel painting, or read or watched The Land that Time Forgot, The Lost World, Journey to the Center of the Earth, One Million Years B.C., The Flintstones, any stop-motion film from Ray Harryhausen, etc., you’re going to feel right at home.
Rotten at the Core is Part 5 of the series, suitable for characters experienced with the Timeless Valley. Four to six characters of levels 6-8 should find the various encounters
presented herein challenging but manageable (who are we kidding? This is getting to the end of the series; the PCs are going to die). A good mix of classes is important, and classes with a nature focus are important for success.