The whole field of view thing with walls and darkness was a really cool idea, great job! Your AI kind of jump scares the player since it doesn't track the player when not in the players field of view, this is awesome, but after that initial scare, I wouldn't recommend he stops every time the player doesn't see him, you can kind of break the AI this way and cheese the levels, after you first see him I would recommend setting some variable for him being activated and then have him constantly track the player, and maybe make his movements just a little more inconsistent than constant tracking. Great game though!