I didn't for this that much. The best part about it is probably how simple it is to understand. It's strange, because that's also a reason why it isn't that good. There is just so little variety in this. You don't get a sense of going on to do different things. Of course, I'm not going to blame this for failing to be something it wasn't trying to.
There could have been some music. You should have made it so that there were more ways to shoot the zombies. There were just two spots for them to be injured. On the plus side, they were injured very badly in those areas. You need more of a challenge.