Hi! I'm sorry that you are experiencing difficulties, but I will try to help you. The game requires at least some mid range PC, so I've seen shadow artifacts and jumping bugs on low end PCs, but nothing like this. Turning the head (looking around) should always work, maybe it's something with your mouse settings? As for the menu button, which menu button? Main menu is made as a room with objects serving as triggers and there are: 'Start', 'Options', 'Credits' and 'Exit'. They are activated on 'E' key when looking at the object or text representing the action. So, for example: you enter first level by looking at the door or 'Start' text and pressing 'E' on you keyboard. And when you are in the level itself you can only hold Esc to go back to main menu room.
If it still doesn't work, maybe you could record a video and send it to me so I could see what is going on, or maybe I could help you via Team Viewer remote connection software.
