MirrorMoon EP is a puzzle game through the exploration of planets and star systems in outer space. The player takes controls of the space ship Boatswain and gets to visit different planets. A large part of the game is spent figuring out the controls of the ships. There are many monitors, buttons and levers each with their own function, but the main goal is to locate planets on the galaxy map and visit them with travel in real time.
There are thousands of systems in each galaxy and each planet has a different look and holds a different set of puzzles based on a number of options and variables. Once the planet is reached the player gets to explore it. The basic controls are centered around using and upgrading a tool that allows the player to control the titular mirror moon near a planet. The moon reflects the lay-out of the planet the player is on and thus acts as a map. The tool can be used shoot waypoints, rotate the moon and even move it. These techniques are used to solve the planet's puzzles, unlocking structures and artifacts until the final exit is unlocked.
When playing online players can work together and share their galaxy maps. Once a star has been solved by another player, he gets to name it permanently. It can still be visited then by other players, but only for sightseeing as the puzzles are no longer available. By cooperating players clear the map and work together towards locating the unique anomaly. The game is organized in seasons with a new one when about 50% of a galaxy is explored. Each season can be started from scratch and a new season has an entirely reorganized lay-out. Updates add new types of artifacts and puzzles, also with many references to other indie games.
Players can also choose to do everything by themselves and play privately.