Kingdomino: The Lost Treasures is a mini-expansion for Kingdomino in which mysterious gemstone-filled chests lure rulers to enrich their growing realms. As you expand your kingdom with domino tiles, you may uncover hidden treasures—precious gems that bring additional crowns, but sometimes unexpected risks. This expansion adds a new layer of tactical opportunity to the familiar tile-drafting and kingdom-building experience.

After setting up the base game, Treasure tokens are placed nearby, with two revealed to show available gems. Whenever a player places a domino that forms a square of four differently typed, adjacent landscapes, they discover a treasure. They choose one of the two visible Gem tokens and place it at the intersection of those four landscapes, orienting it as desired. Each gem provides crowns that are added to territories during final scoring, but careful placement is essential—some gems include skull symbols that cause the pointed territory to score zero points, regardless of its size or crowns. Once placed, gems cannot be moved or rotated.

The game ends as usual after all dominoes have been placed. Players score territories by multiplying the number of squares in each contiguous landscape by the total number of crowns it contains, including those granted by gems. The player with the highest total wins. However, there is also an alternate path to victory: any player who collects five different gem types in their kingdom immediately wins the game. The Joker gem may represent any type, making this sudden triumph more attainable—though it provides only a single crown.

—description from the publisher