Diatoms is a puzzly tile-placement and pattern-making game where players create their own microscopic mosaic, based on an obscure Victorian art form.

Hidden in the water all around us are tiny lifeforms known as “diatoms.” These microscopic algae cells come in a variety of exquisite geometric shapes and patterns. Their outer layer is made with silica, giving them a glass-like quality. Here at the Society for the Microscopic Arts, we collect these diatoms and delicately arrange them on slides into beautiful, tiny mosaics. As part of your induction into the Society, you will each create your own entry for today’s Exhibition of Microscopic Mosaics.

In Diatoms, you compete with your fellow players to collect and place diatom shapes into a mosaic form. You take turns placing tiles representing algae colonies. From that placement you earn diatoms of different colors and shapes. You then strategically place these diatoms on your personal board, taking care to consider how your arrangement will be scored at the end of the game. In the base scoring, you'll want to achieve matching colors, shape variety, and symmetry along your mosaic's central lines. Each time you play, you may also have a "guest" judge card that brings a unique scoring criteria to the game.

Diatoms also includes a solo variant where you collect diatom tiles as in the main game while trying to create a mosaic that fulfills specific requirements from mosaic commission prompts.