In Blue Moon, you and your opponent attempt to rally the support of the peoples of Blue Moon and the three elemental dragons behind one of the heirs to the throne - Prince Roland or Princess Elinor. In order to attract the favor of the dragons and entice them into giving you crystal shards of the Holy Crystal of Psi, you must win a series of fights in one of two elements, either Fire or Earth.

This character has a strength of 4 in Fire and 1 in Earth.

The game is played over a series of fights, each consisting of turns for both you and your opponent. At the beginning of a fight, you or your opponent play a single character and choose an element for that fight. The next player then plays a single character and may also add a booster or support card from his hand. The strength that each player declares each turn must be at least equal to his or her opponent's strength, and as a fight progresses these strengths will continue to escalate. Eventually, one player will be unable to continue the battle and must retreat, at which point the victor of the battle will attract one or more dragons to her side, or pull them away from her opponent and into the neutral area in the middle. The retreating player then starts the next fight.

The game continues in this manner until one player manages to attract all three dragons to his side and then attracts further dragons, or until one player completely exhausts both her deck and her hand. The winner is the player with dragons on his side, who is awarded crystal fragments according to how many dragons he has attracted. A new match then begins, and the first player to amass five crystal fragments is the winner!