Well, yes, the scientist, you know... They experimented with viruses... Of course they botched it and now were infested with zo:mbies. The usual.
Its of course up to you to go clean up this mess by making an even bigger mess of zo:mbie parts.
* 50 levels of mindless zo:mbie hunting
* 10 different weapons, such as a chainsaw, assault rifle, flamethrower...
* Game center integration