Castles by the Sea is a puzzly sandcastle-building game for 1-4 players. As a group of tiny folk called "shorelings," your goal is to build and populate a seaside kingdom. Each turn, you'll place blocks and meeples on the map to earn victory points. The core gameplay is similar to abstract strategy games like Santorini, in that players must optimize three-dimensional placement on a shared grid. Hazards are the only source of randomness in the game, and even those depend on player choices. Each turn, you must choose your placement carefully, optimizing your score while interfering with your opponents' plans. The game ends after a set number of turns. Few castles will remain standing after a final onslaught of hazards, but the kingdom with the most sand dollars can claim victory.