If you can't beat the Tutorial area then there may be no hope for you.

Items Located Here:
Battery - The first battery in the game, will be coming back for this fella later.

2 Green Key cards - Both are one time uses.

Lock-pick - Now no longer infinite.

Red Key card - One time use.

Jack Rod - Don't really know what to call this. Used in a Previous Tutorial Room.

Pistol - Your new best friend. Located in Security Post.

Screwdriver - Any vent crawler's best friend. Located in the Shaft Room.

Jammer - A whole lot less uses this time. Found in... Jammer room.

Note: There is a single Medkit found in an Alarmed supply box in the Pipes room, as well as there being a flooded room with 20 Pistol Rounds near the Shaft room through a covered Vent.

Not much here during early game. But is one of the more extensive areas mid to late game just behind Technical.
NOTE: There is door in Showers (Medical) than can be opened with an Orange Key Card, It is a TRAP. There are 3 O-Cards with 4 Orange Locked Doors.

Items Located Here:
2 Fuses - Get the first really early and the other later. Located in Watchman &
Fuse 1:
Fuse 2: Go Left

Pouch - Ah two spare pockets. Lots of Parkour. Also two pick-locks on the route to the Pouch. Requires the Screwdriver in order to remove a vent cover.

Crowbar - One Helluva fight for the damn thing. Found in Bot Arena. Used in Technical and Engineering.

Orange Key Card - A very long process with 2 lockpicks and a Ammo Capacity upgrade along the way. Requires Crowbar.

Battery 3 - Truly most prized item. Used in the elevator shafts to power it. Must have at least two.

Wrench - Truly the Holy Grail leading to a DMG upgrade in Surgery (Medical).

2nd Orange Key Card - So many Oranges. Need 2 Batteries and the Blowtorch to access. On Level G of Engineering. You can use the Key Card on a door on Level G of Engineering.

Is very intertwined and crosses into Administration a lot.

Items Located Here:
Multiple Lock-picks - Usually on Haydee Corpses.

Wire Cutters - Truly the best item to have on hand. Used everywhere. Found in Dining Room.

Knife - Why must it be found so early. Found in the Kitchen. Used in Medical.

Wifi Remote - Get this early and it will be useless for a long time. Used in multiple spots.

Hard to remember when Security ends and Admin begins.

Since both Wire Cutters and the Knife are found in the Dining Room which is the intersection point between the two Administration halves and Security I will be placing them in this section too.

Wire Cutters - Truly the best item to have on hand. Used everywhere. Found in Dining Room.

Knife - Why must it be found so early. Found in the Kitchen. Used in Medical.

SMG - A bit better than the Pistol. Found in an Access Tunnel going from Technical into Admin.

Arm Band - Free rides too. Used in Security for a Pouch upgrade. Found in Gym

Wifi Button - Locked in the... well... Locker Room. Requires Sledge to Acquire. Be Prepared for a fight.

Rebreather - Is only really needed for two parts. Used in Medical. Need lots of med-kits for the no rebreather cheevo. Requires Wifi Remote and Wifi Button to retrieve.

This area SUCKS between the new battery power pipe puzzle and the no fire zone its very difficult and annoying at times.

Items Located Here:
Battery 2 - Truly the most sought after item (Behind ammo). Found in Supervisor, but has to first be accessed through Elevator. Used in the Power Pipe puzzle in Technical.

Power Card - There are 2 of these first is located in a unmarked room in Elevator and the second is in _. Both cards are placed into the machine where the first card is located powering up the Technical elevator.
Card 1:
Card 2:
Elevator Power:

Screwdriver (Technically) - Can use a vent to unlock the Checkpoint in Tutorial and retrieve the Screwdriver from the item box.

Bolt Cutters - In the Weapon Free Zone. Used in the Start room to access Medical and in Admin to access the crossroad switch button.

Magnum/Rifle - Best Weapon. Need two Batteries to access.

Blow Torch - Free Blowy. VERY deep in the no weapon zone. Need 2 batteries on green and blue to access. Can be used in multiple spots in Technical and a spot in Level G in Engineering.

Red Key Card - Hmm yes Red. Must have all 3 Batteries. A lot of parkour in weaponless Technical. Used on lowest level of Technical, in Gallery.

Code Cracker Thing - Blackberry. Very long process to get to. Requires 3 Batteries to access and doing the power pipe puzzle in Weaponless zone. Note: Both the room it is in and the next room are EXTREMELY COMBAT HEAVY. You need to retrieve your weapons through a vent behind the red key card door that leads into the area where you send green and red power up. Code Cracker is used in Medical to get the 4th Battery.

Mid game area, instead of Gas its water and clunk swimming mechanics.

Items Located Here:
Yellow Key Card - I keep calling it Gold Key Card. Found in Reception behind the Desk. Requires Knife to acquire.

Shotgun - Better than the SMG. Requires the Security Jammer to acquire. Don't have Photo because Pistol only run.

Spare Button - Very easy to miss depending on how you navigate the room. Used in Maintenance (Medical).

Sledgehammer - 'Eavy 'Ammer. Needs Button to access. Used in Medical & Administration.

Wheel Crank - Very watery. Used right outside where you get it.

2 Canisters - Not hard to find really. Used to open Storage. Careful when picking them up it will spawn enemies after picking them up. Bring lots of Ammo and good Reflexes.
Canister 1 - Spawns Slasher Close and a Walker at the door you entered from.
Canister 2 - After picking it up enemies spawn in the previous two rooms.
Use Canisters Here:

Teal Key Card - Teal or Cyan not sure really. Used in upper Medical. Ambush on the stairs.

4th Battery - Truly Tedious. Requires Code Cracker from Technical and the Cyan/Teal Key Card.

Pouch Upgrade - Hmm Pomkemt. Requires the Spare Button in Office (Medical) and optionally the WiFi Remote and WiFi Button, but you can just walk all the way around after getting the Sledgehammer which is in the same room.

Hmm yes Dark and Spooky. Literally only two items here. Also overflowing with enemies, hope you saved enough ammo.
Need 4 Batteries and the WiFi Remote and Button to progress further into this area.

Items Located Here:

2 White Key cards - Both are able to be obtained by going down two different routes. Used to finish the Game.
Card 1:
Card 2: