Circadians: First Light is a sci-fi strategy game in which players lead a team of researchers exploring the planet Ryh. As members of the Circadians expedition, they must complete their mission while maintaining peaceful relations with the planet's inhabitants.

The expedition is tasked with negotiating with the planet's three clans, collecting organic samples for the Moontide repository, and helping secure the future of the Circadians.

Over the course of eight rounds, players manage their crew, represented by dice, to visit different areas of the planet for trading, farming, construction, and research.

Victory points are earned by negotiating with local clans, harvesting resources for the repository, upgrading the research base, exploring the planet, and collecting gems. After the eighth round, the player with the highest score wins.