Harry Potter and the Half-Blood Prince is based on the movie of the same name. The player takes the role of Harry Potter who has to fight against Lord Voldemort and his minions.
The game features an open school environment, allowing players to explore Hogwarts at their own pace between chapters. Portraits can be used to teleport instantly to a desired location, while calling a ghost provides additional guidance on finding hidden crests - 150 collectibles that unlock achievements and trophies. However, Harry's limited jumping ability requires him to use spells to reach the crests.
The majority of gameplay is spent in three mini games: magic duels, brewing potions, and quidditch. Magic duels involve learning new spells by defeating opponents, while brewing potions requires recreating recipes using ingredients within a time limit. Quidditch is a reaction test where the player controls Harry's broom, moving it to fly through rings or avoid obstacles.