2006 · キャンペーン設定（ゲーム世界）
Ptolus: Beneath the Streets
This fantasy roleplaying supplement explores the subterranean world beneath the city, including an ancient labyrinth, the Undercity, sewers, a dwarven ruin filled with treasure and traps, and natural caverns inhabited by dangerous creatures. It provides locations and details for adventures below the streets, and can be used on its own in city-based d20 campaigns or alongside the other volumes in the series.
スキルベース（スキルを購入または獲得）属性／ステータス制（STR、CON、PERなど）レベル制（XPを獲得してレベルアップ）
ゲーム情報（人数、プレイ時間、対象年齢、クレジット）の出典：BoardGameGeek。