In the options menu, access the cheats sub-menu. Enter the following codes for the desired results.
Et In Arcadia Ego: Unlock all bonuses.
Apocrypha: Unlock all Visual Database entries.
Sacred Feminine: Double Health.
Vitruvian Man: God Mode.
Clos Luce 1519: Level Select.
Phillips Exeter: One Hit Fist Kill
Royal Holloway: One Hit Weapon Kill