Harry Potter and the Half-Blood Prince (Xbox 360, PlayStation 3, Wii/Electronic Arts/$49.99) is the typical movie tie-in game, offering just enough movie content to entice the curious, and just enough gameplay to hook the kids.
The game casts an illusion of open-ended gameplay, allowing players full range of a beautifully crafted (and largely faithful) Hogwarts Castle. While it can be fun to wander the grounds, there are no mysteries to stumble upon or quests to acquire while doing so. Instead, the only challenge is acquiring the 150 Hogwarts crests hidden about the castle using one of a handful of arcane utility spells. These spells—wingardium levioso, incendio and depulso—are executed through certain joystick gestures, and are easy to master.
The "[insert hidden item here] mechanic" was fun the first time I saw it in Grand Theft Auto III; since then it's become an overused cliche, and I would have happily ditched it in favor of a more straightforward mini quest mechanic. Delving for hidden crests could be forgiven, but what can't is the "mini-crest" game, in which small, multicolored crests are hidden inside the castle's torches, lanterns and other light sources. Revealing them with depulso causes a shower of rainbow-colored crests to rain down, which you can then collect to trade in for full-size crests. It's a gimmick that worked in LEGO Star Wars, but it doesn't fit the darker, angsty tone of the Half-Blood Prince.
The majority of the Half-Blood Prince game involves three kinds of mini-game. First is a wand duel in which you again use joystick gestures to cast spells. Harry evokes stupefy, expelliarmus and a handful of other spells as he battles bullies, Malfoy and his minions, other students in dueling clubs, and Death Eaters. The duels are easy, and even boss fights are rarely lost.
The Quidditch mini-game involves chasing the Golden Snitch through an airborne obstacle course of glowing stars. It's an approach that had potential—after all, most Quidditch games we see are all about catching the Snitch—but the lack of any real obstacles, Harry's tendency to stop awkwardly when he hits terrain and the game's decision to ignore the rest of the Quidditch match (including errant bludgers and the other players vying for the Quaffle) makes it just another ho-hum obstacle course.
The last mini-game involves potion creation, which makes sense given that Harry learns of the Half-Blood Prince when he accidentally picks up the prince's potions textbook. Potion creation is a simple pattern-matching game in which you race against the clock to craft your concoctions. It's a fun little game, and probably the most challenging of the three (though that's not saying much; you're still much more likely to pass than fail).
Die-hard fans looking to mine the game for insights into the movie will be disappointed. While the game does hit on the major plot points of the book and movie—Harry Potter's growing affection for Ginny Weasley, Ron's relationship troubles, Harry's attempt to uncover Draco Malfoy's nefarious plot and Dumbledore's research into Lord Voldemort's past—it does so in a disjointed way that's sure to confound newcomers. The game jumps from plot point to plot point with little in the way of exposition; one moment Harry's at Diagon Alley shopping for school supplies, the next he's confronting Malfoy on a train, the next a student is being cursed in a snow-filled Hogsmeade and it's Christmas break.
The game's marketed as a family game, and by that standard, it will likely succeed. It's two-player dueling club, the mini-games, and even the annoying rain of mini-crests could appeal to younger kids who've read the books and are itching to see (or replay) the movies. For the rest of us, it's best to just throw an invisibility cloak over the thing and be done with it.