At the moment I'm thinking of cannibalizing my Gamma World fourth edition & Mutant Future rpg campaign notes with dealing with planes especially dusting off my
Looking into my Cha'alt/Godbound campaign means that I started looking into Skirmisher Publishing's Quantum Flux; "Quantum Flux contains 86 unique superscience artifacts suitable for use in any modern, sci-fi, or post-apocalyptic setting, and range from amulets to buildings." Quantum Flux was meant for Goblinoid Games Mutant Future rpg & works well with Gamma World fourth edition. I used this book and other Mutant Future resources for a planar breech New York City campaign location. That breech is going to be coming over to my Cha'alt campaign.
All of these resources work with Jeff Grubb's Advanced Dungeons & Dragons Manual of The Planes. And thus first edition AD&D becomes a vital resource for planar campaign. These resources are vital part of a campaign chain.
As I continue writing the Lovecraftian campaign Realms of Crawling from Goblinoid Game the relics & artifacts in this book are going to start popping up in the treasure piles and ruins. Many of these are going to be from else where & dropping into the hands of various cults across the United States.