The darts are handy for destroying baddies like Stay-Puft's marshmallow minions - hellhounds made out of sticky white goo. They explode satisfyingly, coating everything and anything nearby, including you. But for the most part enemies can't be blasted - you have to capture and trap them.
This means targeting them with your proton stream, first of all, using the analogue sticks and right trigger. The stream is easy to aim and control, and you can earn upgrades to make it even more precise. Once you've got a lock-on you can press the left trigger to slam the ghost around the environment, thereby tiring them out and making them easier to handle.
Press X and your character will chuck out a trap, clearly visible by a beam of light that extends upwards. Drag the ghost into the beam and it will open up into a cone of light. Then it's a matter of wrangling the spook downwards, using the sticks to make sure it doesn't escape out of the cone along the way.
The mechanic will be familiar if you've ever played a fishing game, and capturing ghosts is just as satisfying as hauling a great big bass onto the deck. The controls are sensitive and refined, so you really do feel like you're struggling to keep the ghosts in position. The traps shut with a nice loud snap, which is your signal to walk over and pick them up, still smoking. Your character carries three or four traps at a time, so it doesn't matter too much if you lose track of one or just can't be bothered to go and collect it.
The other key piece of equipment is the PKE meter. Activating it gives you night-vision goggles, essentially, which are capable of detecting ghostly energy. The PKE is also used to scan spooks; this adds information about them to your database for reading later. Again, it's a feature that's really only for the fans, but it's a nice addition - particularly as the enemies, designed with input from Aykroyd, are varied and inventive.
Of particular note are the monsters in the library level, who are constructed from dozens of books and also use them as makeshift shields. Their movement animations and the physics involved in battling them are highly impressive. Then there are the valkyrie ghosts outside the opera house, big fat Brünnhildes who swoop and shriek all around you. But the real star of the show, of course, is Mr Stay Puft.
He appears in the best of the levels I got to play, which begins in Times Square. It's beautifully rendered, the bright billboards flashing and blinking with tons of detail. Cars and marshmallow goo are piled up in the street, blocking the path of Ecto-1. You don't get to drive the car at any point (they've got to save something for the sequel), but you walk alongside, guiding it to safety.
And then Stay Puft comes looming out from between the skyscrapers. It's a great moment, especially when he starts stomping towards you. There's a real sense of his huge scale, and of fear that you'll get crushed underfoot or swept away by a giant hand at any moment.
Naturally Stay Puft can't be taken down by a few quick proton blasts, and the next part of the level sees him swiping at you through windows as you run round an office building. Again, it's a real thrill the first time his huge staring eyes appear at the window, and when his giant arm bursts through the wall.
The final section of the level sees you suspended over the edge of a skyscraper, blasting furiously away as Stay Puft clambers up towards you. As boss battles go it's not the toughest challenge you'll ever face, but it's fun. Besides, I'm playing on the normal default difficulty level - there are options to make the game harder, or easier for more casual players.