Excuse the blatant necroposting, but I like to revisit things every once in a while.
GAME MECHANICS:
I'd like to consciously avoid anything too similar to
Ghostbusters: The Video Game here, and the best way to do that is to simplify the ghost-catching concept. Instead of “draining their PKE,” your goal is more to herd them ever closer to the trap. In other words, it's a capture stream throughout. I can safely say that
GB:TVG would probably have benefited from a lock-on feature, in that you could keep your sights locked on to a ghost and then follow him around with the stream, as opposed to just firing the nutrona wand blindly.
The idea of the Proximity Trap is nothing new, and it translates well to gameplay in a way that a manually-controlled trap wouldn't, so I'll leave it in.
“Wrapping” a ghost involves turning the C-stick (this is a Gamecube controller) once you have the stream trained on the ghost and have made a few seconds' contact. Once you've wrapped the stream around him, you then have to wrap a few more layers, which makes the stream ever shorter. Don't get too close or the ghost will try to slug you and escape the stream!