Depends on the system you use. Most common system worldwide and in the academic circles (the oldest of the two) has 1 as the answer.

This is the best video out there. A lot of people in north america have no idea.

10 bucks for this game a a steal. The atmosphere and worldbuilding is amazing. It feels mysterious, creepy and there are some really unique moments that mess with your head. The action is fun and challenging at times. This is not a typical shooter though. And you have to be ready for weirdness. :)