Could this be the Ultimate Crossover?

"The Dread House" by Danny O'Neill.

Published and Distributed by Hammerdog Games.

ISBN-10: 1-59180-057-9 -- 288 Pages.

I recently bought "The Dread House" by Danny O'Neill. If I had known that it was going to be =this= good, I would have bought it =much= sooner.

The Dread House is a take on one of the oldest tropes of Role-Playing Games - a Haunted House. The most important feature of this book is its compatibility with Pathfinder 1.0, and 5th Edition D&D, =and= Call of Cthulhu!

I cannot think of any other product that claims the distinction of having D&D, Pathfinder, and Call of Cthulhu in the same volume! Given this, there is a very real possibility of being able to have PCs cross over from one system to another system to yet another system!

In the darkness, an old ruined manor house sits -- waiting for its next victim. If this sounds a bit like "The Shining" to you, you are close to correct!

There are only three sections in the book:

1) "The Time of Myth and Magic: The Dread House in Medieval Times".

2) "The Time of Mythos and Machine Guns: The Dread House in the Roaring 20's".

3) "The Time of Connected Dependence: The Dread House Today and Tomorrow".

There are dozens of full-color maps of the manor, including a master map on pages 54 and 55. Each section of the house is broken down into smaller pieces, each appearing in an appropriate section of the book. The marvelous map of the area beneath the manor should drive prospective players who map insane, for tunnels twist and turn, frequently overlapping each other. The chosen artists have been selected well. All of the included art matches the tone of the setting.

Section 1 - "The Time of Myth and Magic: The Dread House in Medieval Times"

Storyline One: "The Dread Wedding". This is what happens that makes the Dread House haunted. This occurs in a Medieval setting. "The Dread Wedding" is presented as it happens. PCs may try to stop this from happening, but this is difficult since the Dread House also exists in the 1920's, and the modern-day, and even possibly, in the future! In addition, in order to truly end the reign of the Dread House, they must complete the second part of the story.

Storyline Two: "Scions of Solaria" is also about the Dread House, but the PCs are led to find eight different parts in this prequel to the "Dread Wedding" and this can take beginning Pathfinder or D&D characters from Level One to Level Six. In this chapter, there are references to "Solaria", Goddess of Life and Light. Complete information about her is found in the back of the book. Copying the single page about Solaria might be a good idea, since at least one, if not more, party members should worship her.

Both of these sections includes info about 5th Edition, Pathfinder, and Call of Cthulhu.

Section Two -- "The Time of Mythos and Machine Guns: The Dread House in the Roaring 20's"

Storyline Three: This section is designed to work best with Call of Cthulhu, but also has stats for 5th Edition D&D and Pathfinder 1.0! It is divided into six scenarios:

1) "Piercing the Veil"

2) "13 Ghosts"

3) "The Tome of the Dead"

4) "The Machine Man"

5) "Ghostcatchers"

6) "Dread Secrets"

This part can span a timeline of sixteen years! There is a small piece of fiction about each of the six parts. Each of these six scenarios may be run as stand-alone adventures.

"Section Three: The Time of Connected Dependence: The Dread House Today and Tomorrow".

Storyline Four: Because of (I believe) the Call of Cthulhu material, the manse can also exist in the modern-day, and even in the future! Storyline Four consists of two sections:

1) "Stay the Night" and

2) "Geist in the Gears".

At the end of the book are three good appendices, which include "Optional Rules", "Dread Ghosts", and "The Arcane and the Eldritch". A GM toolbox at the end has a nice summary of effects. An advertisement for their other mega-dungeon, "The Grande Temple of Jing" ends the book. There is no index, but a good Table of Contents.

I was impressed enough by "The Grande Temple of Jing" to seek out other products Hammerdog produced. This book even exceeded my expectations! If you like Pathfinder 1.0, and/or, if you like 5th Edition D&D, and/or you if like Call of Cthulhu, I think you almost can't go wrong by picking this book up! If you like two or all three of these, my suggestion to you is to buy this! This book now has the distinction of being in my "Top Ten Gaming Books of All Time" list!