These items are obtained through the course of the story, and are vital for your survival and the progression of the game.
These items are unlocked through finding blueprints through the course of the campaign and are made in the crafting submenu, combining items together to create useful weapons, distractions, and tools.
Weapons, like story items, are accrued through the course of the story. Their usefulness varies greatly depending on the enemy you wish to defeat and the circumstances you are in.
NOTE: No weapon is capable of killing or appreciably injuring the Alien.
All these items are consumable, except ID Tags; once they are used, you must collect more. Only the Flare, ID Tag, and batteries are not components for craftable items.