Play it! Play it now!
Throughout the game there are a number of collectible artifacts that enhance the game but giving you hints and an idea into how it all happened. As well as artifacts there are training manuals that improve your homemade bombs and parts to help upgrade your weapons.
It's not possible to fully upgrade the weapons and characters in one play through either so It's nice that one you complete the game you can start a New Game+ with all of your equipment and upgrades you ended the first play through with.
Can't wait to start my New Game+ and tackle multiplayer. Along with a get story the graphics are amazing and the scenery is really beautiful. I highly recommend this game, you won't be disappointed.