1999 · ソースブック（プレイを拡張するルール／オプション）

Secrets of the Ancients: An Internet Supplement

This netbook expands the post-apocalyptic Gamma Terra setting for the fourth edition of the game. It collects new material alongside revised information originally published on the Internet, including fan-created rules, setting details, and other game resources. Most of the contents are also compatible with other editions.