There are a whole slew of different types of unlockables that you'll be able to snag, including behind-the-scenes footage, artwork, additional costumes and even other playable characters (though Nathan will still appear in the cutscenes). You'll also be able to unlock different rendering modes, like a black and white mode, a sepia-toned mode, a next-gen filter (with appropriate super bloom and saturated colors) and even a mode that doesn't utilize textures, allowing you to see how the geometry was put together more easily. It's worth noting that any unlockables you earn are shared between all the save games on the system, and that you can carry over Medals that you've earned into a second or third play through in order to help you find all the treasures and unlock everything.