We finished the campaign as quickly as we could. xD

And I second everything Vivi says about L4D and scariness. Nothing jumps out at you, because you can hear everything coming - the special infected all make silly noises and they are often pre-empted by some spooky music. Regular infected don't jump out either. They tend to run in herds. There is a lot of blood spatter, but it's not real feeling - it's too campy. xD

The only time L4D gets scary is when you're actually playing it and you are running low on health and you're limping towards the safe room and oh god are you going to make it, and even then it's not scary so much as intense. xD