If you are done with The Evil Within campaign, there is a lot more that you can do. For example, you can unlock weapons and game modes. Below you can see a list of weapons and game modes and how to unlock them.
How to Unlock Weapons in The Evil Within
Machine Gun
The machine gun will be unlocked only after you have completed the full campaign.
Rocket Launcher
Just like the machine gun, the Rocket Launcher will also be unlocked after you are done with the campaign. It is similar to the one seen in the last chapter, and you can use it to kill certain bosses who are otherwise too hard to beat (like Laura).
Automatic Handgun
You can get the Automatic Handgun once you are done with the archive.
Burst Handgun
This baby gets unlocked only after you have worked hard. You will have to find all the 28 Map Fragments in order to get your hands on it. It is actually a pistol that can fire bursts.
High Powered Sniper Rifle
Just like the burst handgun, you will have to find all the Map Fragments in order to unlock the High-Powered Sniper Rifle. It is much more balanced and much more powered weapon than the standard Sniper Rifle.
Brass Knuckles
Nothing compares to a devastating melee attack but you first have to earn it. Only after you have completed the campaign on Nightmare difficulty will you unlock Brass Knuckles. They will make your melee attack much more powerful.
How to Unlock Weapons in The Evil Within
New Game+
Once you have completed the campaign this new game mode will be unlocked. It lets you replay all the saved chapters again but this time with special unlockable weapons.
Nightmare Mode
You only get to act like a pro when you have proven your worth! This mode kicks in after you have completed the whole campaign. It gives you the game at a much harder difficulty with less ammo and much more powerful enemies.
AKUMU Mode
This is not for the faint-hearted. Once you have completed the campaign for the first time you get to play the AKUMU Mode where Sebastian will die only after the first hit.