Capture the Flag is a long-time tradition in Camp Half-Blood and is held every Friday. The campers usually play amongst themselves, but when the Hunters of Artemis visit, they face them in a "friendly" match.

The setting of the game is the forest, where the monsters are located and hiding. It's a very dangerous game, but it is beneficial for the demigods because it gives them real life training for the real world.

Two teams are made, and each team has a flag. On each side of the forest, both teams hide their flag somewhere visible, but easily defensible. To win for your team, you need to capture the opponent's flag and carry it across the river that divides the middle of the forest, and acts like a border.

Chiron, the centaur, serves as battlefield medic and referee.

In The Demigod Files, it is revealed that there is a Capture the Flag jail. Captured opponents can be placed in the jail and aren't allowed to leave unless freed by another person from their team. Annabeth Chase and Silena Beauregard managed to take Percy Jackson and Charles Beckendorf away to jail when they played against each other.

According to traditions, whenever the Hunters visit the camp, a "friendly" game of Capture the Flag game will be held. As of The Titan's Curse, the Hunters had won the last 56 games in a row (much to Chiron's and the campers' dismay).