Not bad! Once I was getting attacked by constantly flowing hoards of zombies and slipping around on the pathways of blood I had been constructing it was a blast! It perhaps, however, took a bit too long to get to that point, and maybe it was a little too easy to completely refill your health. I stopped slipping around after I realized if I just waited for them to group up around me and slowly shot at them I would never lose. Still, not bad!