1993 · ソースブック（プレイを拡張するルール／オプション）

Chessboards: Planes of Possibility

This roleplaying reference provides gamemasters with a flexible system for designing and developing planes, including their types, relationships, growth cycles, and methods of interplanar travel. It offers guidance for using multiple settings in one campaign or connecting several campaigns within an organized multiverse. The book includes five sample metaplanes, along with optional rules for planar energy, artifacts, and interactions between planes and deities. It is designed for use with any roleplaying system.