You are playing as 2 persons. Mark and Simon. You will be able to change between these characters... and others...
10/10, would not play again (because I'm still shaking like a leaf).
Okay but seriously, there were some beginner mistakes (a billboard sticking through the wall in the first map) - but they're completely forgivable because, well, you were a beginner when you made this and basically all of the scripting/story/atmosphere/scares were amazing.