In terms of gameplay, Ghostbusters plays out like a weird cross between Gears of War and the underappreciated GameCube launch title, Luigi's Mansion (not that Nintendo can complain, given how much Luigi's spook-hoover owed to the classic Proton Pack). You and your fellow Ghostbusters wander around the game's various NYC locations, dispensing hostile spooks with the aid of proton pack and traps. While some incorporeal entities can be simply blasted into atoms, most need a three stage process where you a) shoot them with the proton stream to wear them down b) capture them with the stream and slam them against the scenery to wear them out then c) drag them into the beam of a carefully thrown trap for capture. Once one encounter is over, you use your handy PK meter to find the next, effectively following the trail that leads you from spook to spook to spook.
Be warned: Ghostbusters is a heavily scripted game, to a degree that makes Call of Duty: World at War feel like S.T.A.L.K.E.R. by comparison. There's no real room to explore, the level designs are artificially linear, and you'll find yourself countless times awaiting some scene to play out before you can get into the next bit of action. If you want puzzle-solving, adventure or complex tactics you won't find it here: appropriately, this is a big, fat ghost train of a game, shuffling you along the tracks from one spooky combat set piece to the next.
This should make the game boring and repetitive, but amazingly it doesn't. For one thing, Ghostbusters mixes up the spook types, adding in new spectral varmints requiring new and special treatment to zap and trap. For another, a steady stream of experimental proton pack upgrades add new types of stream or new abilities that keep the ghost-busting routine from growing stale. Beams can be used to stop fast-moving, heavy hitting ghouls in their tracks, while slime can be used to neutralise caustic black ectoplasm or create ever tightening cables of goo between objects. Boson darks take a role halfway between a shotgun and a rocket launcher, helping to wear down powerful enemies faster, or take out groups of smaller, more disposable foes.
On top of this, all your weapons are upgradable, while the ghosts get more difficult to manage as you go on. The game constantly pushes your skills, but at the same time it gives you more and better tools to work your magic with. The set pieces get bigger and better, old favourites like the librarian and the Stay Puft Marshmallow Man put in an appearance, and locations change from supernaturally flooded hotel floors, through subterranean passages to ghastly other worlds. This isn't the brightest or most intellectually demanding game around, but it works pretty hard to keep your interest.