The campaign of Subterrain follows a specific direction and can be confusing and difficult if not played with the game's goals in mind. This is a short walkthrough to complete it quickly.

• Prioritize junk that recycles to Metal Composite (the yellow square)
  
• Save up at least 300 each of Blood Extract, Tissue, and Osseus. You'll need them in the end and if you spent a lot crafting meds you'll be out farming mutants
  
• Use Decontamination pills when you're out exploring, not home sleeping. That way it protects against future hits.
  
• Nilson Engineering and Murray Space Center have lots of junk lying around to be recycled.

If you opted for the tutorial, you will have to navigate through the Prison complex to reach Central. If you need the tutorial, I recommend restarting your game after you complete it so you don't waste time in the Prison.

Central is always safe. Grab a bunch of weapons from the room in the southwest (also has a bed for sleeping) and pick up some keycards to open the Power Control Room, Nilson Engineering, Herbert Research, and the Generator Room. Once you have the Power room open grant power to the near areas: the Mine, Engineering, Research, and the Biosphere. You can then access these through the terminals in Central. In the Generator Room, the eastern walkway has a storage unit with an extra Power module. Begin researching it and research the Oxygen Filter/Thermal Regulator (keep researching to make better ones). Grab some life support packs from one of the rooms and charge them.

Always have the Mining and Biosphere terminals working on something. Usually quantities 20-30. Don't spend time in Central waiting for things to research. Set a bunch researching and head out.

Tips for exploration:

• Focus on finding the Elevator, Power Switch, and Stairs. Know what the layout of them looks like and try to find them as quickly as possible.
  
• After you switch the power on, open your map. The data chip will appear as a gray chip icon. Don't head to the next floor until you've looked at the map!
  
• Bring the best Oxygen Filters and Thermal Regulators you can make to install.
  
• Don't move on to the next location until you've found the Oxygen and Thermal rooms. You must scout these rooms.
  
• Don't search through every room. If it's filled with mutants and has no other doors, just close the door on them and move on.
  
• Never search Gyms. They contain almost nothing but mutants.
  
• If you open a door and it's just a small bedroom or closet, and the layout of the level seems to indicate another door will be the same, skip it.
  
• Focus looting junk that recycles to Metal Composite, followed by Jewelry/Gems, Medical Supplies, and junk that recycles to Electronic Resin.
  
• Be sure to pick up all the little samples the mutants drop.
  
• Don't return to a location to try to decrease the mutants there, or just to install a better Oxy/Therm module. Keeping moving forward.

Tier 2 data chip order:

• OPTIONAL: Herbert Research - Keycard - Johnathan
  
• Carson Hotel - Engineering 2 (build 2x copies of the software) + Prototype Plasma Launcher Blueprint
  
• Viking Square - Research 2 (build 3x copies: 2x for research and 1x for the repair terminal)
  
• Solar Casino - Mining 2 (build 1)
  
• Spirit Plaza - Biosphere 2 (build 1) + Space Center Keycard on the ground floor

At the first set of locations the Oxygen Room is always on floor 1-4 and the Thermal room is always on Floor 5.

Now it's time to head out. Skip the close areas and instead grant power to Carson Hotel. Bring an Oxygen Filter/Thermal Regulator to install. Take the tram and begin exploring. Remember you have two objectives here: find the oxygen/thermal rooms and find the data chip. Be as quick as you can to find these locations. Most of your time should be spent serching for the Elevator/Power/Stair section of the level which takes you to the next floor. Be sure to find the Oxygen/Thermal rooms as if you don't you will have to later.

Once you've got the Engineering 2 data chip, research it at base and build two copies of the module. Go down into Nilson Engineering and install the software chips.

From there the process is the same for Viking Square, Solar Casino, and Spirit Plaza. As you get the chips you must head down the stairwells to the near locations to install them. Take this time to explore a bit of the locations and install Oxy/Therm modules. One of the rooms in Herbert Research has Keycard - Johnathan. If you take this to floor 5 of Carson Hotel you can get the Prototype Plasma Launcher Blueprint.

Spirit Plaza has the Murray Space Center Keycard on the ground floor in the northeast. Don't leave without it!

By now you should have or be researching a better Pistol, Heatsink, Barrel, Armor, Flashlight, Backpack, Reactor Modules, Oxygen Filters, Thermal Regulators, and life support canisters.

The oxygen rooms are somewhere on floor 1-5 in the next set of locations. The thermal room is always on floor 10.

• District Aries Part 1 - Engineering 3 on floor 1-5
  
• District Gemini - Research 3 (floor 1-5) and Mining 4 (floor 6-10)
  
• District Aries Part 2 - Biosphere 4 (floor 6-10)
  
• District Pisces - Research 4 (floor 6-10)
  
• District Leo - Engineering 4 (floor 6-10)

Start with Aries for the Engineering 3 chip. It will be on level 1-5. Find the oxygen room while you're there as it's on floor 1-5 too. Remember to use the map after you power the floor to find the data chip. Once you have it, clear until you have to go and then head back.

Continue with the next locations. Always find the Oxygen room on floors 1-5 as well as the Thermal room on floor 10.

At the space center in the back is a Space Shuttle. It has a Broken Navigation Module in the nearby terminal. Take it and you can research and make a new one at Central. In the Southwest of the center is a data chip with Space Suit Plans. Use this to build a working space suit. Also make 5 Space Shuttle Fuel. Return once you have everything. Put on the suit, load up the fuel, install the nav module, and hop in.

After wandering through the mansion, get to the second floor. In the room to the east of the closed gate is a large machine with a switch. When you press this switch you will be given the plans to create Purification Filters (Oxygen) and Purification Regulators (Thermal) that will completely destroy the infection. But when you flip the switch you will also significantly increase the rate of the infection until you install those purifiers. This is where having all those Oxygen/Thermal rooms located will come in handy to save you time. When you think you have enough of the Oxygen Filters and Thermal Regulators installed across MPO, flip the switch, take the plans, and use the tram to get to Herbert Research and back to Central.

At Central, research the plans and begin building many sets of Purifiers to install in each location. Save up two sets and head out on the same tram line to install both. When you get back more should be ready and you can continue installing them everywhere. After they're all installed, you'll need to waste some time until they clear the entire infection before moving on.

Stock up on Windroid, Power Pack XLs, the best Armor, the best weapons you have, 40-100 photon grenades, and some of the best Nanocasting, Bandages, and Medical Kits. This is it folks. Head back to the Mansion and the switch next to the gate will now open. This is the end and it will take you to the basement. I hope you came prepared.

The only tip I have for the fight is to run the heck away from him when he does his standing still move so you can put some distance between you guys.