Children of Mana supports DS-to-DS multiplayer cooperative play, and engaging in this mode is the only way to obtain certain unique gems. These gems are not available through single-player progression or shops. To play multiplayer, each player must own a copy of the game; it does not support download play. Playing cooperatively allows you to tackle dungeons with a friend, making some challenges easier and providing access to these exclusive rewards. If you are aiming for 100% completion or want to collect all available gems, you will need to find a partner and engage in multiplayer sessions. The specific names and effects of these multiplayer gems vary, but they often provide powerful bonuses that can significantly enhance your character's abilities. Consult the [GEMS] section for a detailed list of all gems, including those exclusive to multiplayer.
