The game begins at the Quidditch World Cup Campsite, which is being invaded by Death Eaters. Harry and his two best friends, Ron and Hermione, have to escape from these evil wizards. As you run through the campsite, your friends trail behind you, controlled by the game's A.I. One great feature about this new game is that a second player can pick up a controller and hop into the game at any point and take control of one of the two A.I. characters (much like LEGO Star Wars). Your friend is also free to leave the game at any point, returning control of their character over to the computer.
You have three basic spells which are used to get the kids through the dangerous world of Goblet of Fire. The jinx is your basic attack, which you'll use on the various creatures that infest the land. Charms are used to manipulate things around you. If there's a boulder blocking your path, just place a charm on it and move it out of the way. Similarly, fallen trees can be charmed, allowing you to drag them aside. The feeling of tension when charming a heavy object is akin to having a rubber band attached to the obstacle -- the heavier the object is, the harder you'll have to pull to move it. The third wand technique is Accio, which is a summoning spell. When defeated enemies scatter Bernie Bott's Every Flavor Beans, a quick Accio will suck the beans up.
You perverts can now drool over a virtual Emma Watson.
As you cast spells on the game's enemies, enemies will be dispatched in different ways depending on the various combinations of jinxes and charms that you place on them. Although many of the different methods are merely cosmetic, there is a bit of strategy to be had, especially when playing a two-player game. One technique that I would use that works wonderfully is to have one play snag a beast with a charm, holding it in place. Meanwhile, the other player unloaded a fury of jinxes on the helpless monster. As you progress, you'll even be able to upgrade your characters stats, like range of fire and strength. It's not quite RPG level, but it does add a bit more depth to the game.