From publisher blurb:
I've done a lot fantasy - dungeoncrawl, hexcrawl, weird fantasy, science fantasy, dark fantasy, Lovecraftian fantasy... with Stairway of V'dreen, I wanted to create more of the same while attempting to capture something different, so I went with conceptual. It's difficult to explain and I don't want to give any spoilers away. I think you'll be pleased, though.
Along with the scenario details, I've included some cool monsters, NPCs, magic items, and random tables that can be used with the fantasy RPG of your choice. In fact, a couple of these tables allow DMs to have virtually unlimited magic items and monsters! This scenario is for mid to high-level characters.
Stairway of V'dreen was meant for Crimson Dragon Slayer (either version). Crimson Dragon Slayer is like your typical OSR, but with d6 dice pools. Might sound imcompatible, but I assure you their similarities are greater than the differences.