Clank!: Catacombs – Underworld1 to 4 Players Clank!: Catacombs Underworld, the second expansion to this deck building, dungeon crawling game, sees the thieves going deeper than ever before with special new tiles offering entry to a mysterious new realm. Underworld expands upon the push your luck experience of Clank!: Catacombs, with even better treasures awaiting in the deepest areas if you can escape!