Who you're gonna call? 
From IGN:
Ghostbusters reboot is entirely its own beast featuring a mix of
management, driving, and specter-blasting gameplay styles. Its
developers like to describe it as "X-COM light." If you haven't
played X-COM, it's a classic, tactical PC game that splits its time
between managing bases/personell and isometric combat. A big
difference, though, is that action unfolds in real-time in
Ghostbusters, whereas it was turn-based in X-COM.
By performing your civic duty and making house calls you earn
skill points and moolah. From what we can tell there are loads of
skills for the 'Busters to learn and equipment to be bought. The
skills have been tailored to each character. You will also earn
slime from the ghosts you catch, which can be used to research new
equipment like a Slime Gun.
In between missions you'll receive calls for side quests which you
can accept or ignore -- but ignoring too many will damage your
reputation.
The game is presented in a top-down view but environments and
characters have been rendered in 3D. Music from the films will
accompany your adventures, but none of the voice work from the
console games is included. This is partly due to the limitations of
the DS and also because this game is its own product with a unique
storyline. While players step into the proton pack of a new recruit
on the consoles, here we'll be controlling the original Ray, Peter,
Egon, and Winston.
Ghostbusters: The Video Game is scheduled for release in
conjunction with the 25th anniversary of the first film, which will
be June 2009.