The game is very similar to the previous one, with its Wide-Open Sandbox version of Hogwarts getting reused with few changes. Once again, Harry is the Player Character, although there are brief sequences in which you get to play as Ron and Ginny. And while some of the film actors voice their characters for this game, it's fewer than last time.
There are three types of Mini-Games. One of these is a Potion-Brewing Mechanic, which makes sense considering the important role that potion-making plays in the plot of the sixth book and film. Another is Wizard Duels, complete with the old Dueling Club being restarted. And finally, Quidditch is playable for the first time since Chamber of Secrets.
- And Now for Someone Completely Different: You're Ron when he's under the influence of Romilda Vane's Love Potion and Ginny when she temporarily replaces Harry as Gryffindor Seeker.
- Final Boss: Bellatrix, kind of. You fight a series of Death Eaters, ending with her. Harry tries to fight Snape in the concluding cutscene, but fails as per the plot.
- Foregone Victory: Crabbe and Goyle attack Harry after he takes the Felix Felicis, and in the ensuing duel, they are unable to hit him. Also while under Felix Felicis, you brew a potion which is impossible to screw up.
- It's Up to You: The Burrow is attacked by Death Eaters and while you (as Harry) fight, Ron and Hermione hang back and do absolutely nothing except yell pointless advice at you.
- Nobody Poops: The boys' restroom is full of urinals but has no stalls.
- Potion-Brewing Mechanic: Of course, the original story involved the Half-Blood Prince's book turning Harry into a whiz at potions, so it's only natural that making potions would be a major feature of the video game. However, the game tries perhaps a little too hard to shoehorn in as much potion-brewing as possible. For instance, when you attend Slughorn's Christmas party, he randomly expects you to whip up a punch for his guests.
- Record Needle Scratch: Used when Harry and Ginny start to have a "moment", but then Ginny mentions she's going to Hogsmeade with Dean. Yes, really.
- Shaped Like Itself:Goyle: Hey! You losers from the Gryffindor loser team of... losers.
Katie Bell: That's imaginative. Did you think of that or did Malfoy?
- Suspicious Video-Game Generosity: Before the climax of the game begins, Dumbledore directs you to make a Wiggenweld Potion for yourself and he won't take you to the Horcrux cave until you have it.