HI and welcome! I'm sure that there are many of you out there who are long-time sandbox lovers, and that there are many of you out there who are hardcore gamers. Of course, those of you that wish to put the two together in their next (or current) subnautica players likely found your way here. So, I cleared the post-launch hardcore mode, and many of you are wondering on how to do the same. So, I've provided some information that will (hopefully) speed you toward your goal of getting off 4546B without dying!

Note: This guide may contain some spoilers, but don't expect a ton. This guide is also not extremely in-depth, for the sake of avoiding as many spoilers as possible, but when they show up, they will be properly blacked out for those of you that haven't yet gotten to their relevent points, and don't want anything spoiled.

For your own sake, I hope you know what you're getting yourself into; hardcore mode can be EXTREMELY grueling.

Finishing Subnautica in hardcore isn't going to be easy (yeah, duh.) and you have to be prepared for that. You're might die, and some think it's practically unavoidable; I'm here to tell you that it's not.

However, if you want to beat the planet, you're going to have to be prepared to get back off your feat after you've lost anywhere from 2-20 hours of gameplay. This might come in the form of death, or you getting your stuff destroyed by some beastie.That might not be easy for most people, but if you want to win, you have to accept that at some point, ♥♥♥♥ might hit the fan, and you just have to go back, try again, and try harder.

That being said, the outcome you want is never the one where you drown 10m from the surface, or get snapped in half by a Leviathan. Herein, you're going to figure out some tips on how to avoid that sort of thing.

Sometimes having a little bit extra of something can be the difference between life and death, and of course, you're always aiming for life. You always want places to put things, so don't be afraid to go crazy with increasing your storage space. Specific things you want to do include:

• Having a large amount of titanium on your
  person AND in your base at any given time.
  
  
• Always having enough batteries, and then, having some extra batteries just in case.
  
  
• Have a seperate set of tools, another seaglide, and a spare seamoth just in case never hurts.
  
  
• Keep caches of food and drink, and try to reserve consuming food blocks for special occasions, specifically, when there is nothing else you can eat. (This ensures that if you ever dig into your emergency rations, they will last considerably longer.)
  
  
• Carry at LEAST three first aid kits, and some food/water on your person at any given time; you never want to be caught without these essentials, especially when you need them.
  
  
• Don't stray too far from an oxygen source, and keep your tank at least 60% full at all times.

Furthermore, you always want to gather more than you need when you go out. This ensures that in the future, if there are complications with finding what you're looking for, or it might be extremely dangerous to go out, you have everything you need.

Safety is the #1 priority here. If you can't stay safe, you're going to have a very difficult time staying alive. Leave the riskier decisions to the people who know that if they get wolfed down by a sea monster they can respawn and shake it off. You're not one of those people. This can will change how you play, so don't fight the differences in play style, embrace them.

Remember to be very judicious in how you play, and to always weigh the pros and cons of what is about to happen. For instance, you don't need that extra piece of metal salvage surrounded by a hungry pack of very toothy sea animals, and you don't need to get close enough to scan that leviathan, because you don't need a scanner to know that it's going to want to eat you. On the rare occasion that you absolutely must cross paths with an entity or situation that could mean your demise which you absolutely cannot avoid, always remember to come overprepared, and armed to the teeth. A few example situations for this would be trying to get around the Ghost Leviathan when entering the lost river, or avoiding the Sea Dragon when attempting to access the ancient alien facilities buried deep in the lava zone. So don't forget to have shields and torpedoes at the ready when you need them.

Always have more than one route from which you can approach a situation, to make sure that there are always options. Failing to do so may put you in the position of feeling like the only way forward is extremely risky, but not wanting to turn tail and return home either. This is not a good place to be in; you always want that third option. Furthermore, you always need a plan for if things go haywire, because it's always better to have something to fall back on, instead of dying outright. Some specifics to keep in mind include the following:

You always want to keep a seaglide on your person, even if you don't think you're going to use it.
It's also good to have a stasis rifle or some other form of self-defense on your person. If you haven't yet found a stasis rifle then the enemies you're fighting can likely be deterred by using bait, or a propulsion/repulsion cannon.

Don't forget to fill up a storage container on your vehicle with backup food, water, first aid kits, and batteries, and always have a few of each on your person. You never know when your supplies are going to run out and you'll be forced to rough it.

This goes for food too; it's always to have a farm in your cyclops and a farm in all of your bases, as marble melons are a great source of food and water. Having lots of plants ensures your food and drink won't run out immediately. Keeping bottles of bleach on board a submarine also help with this, and it's not a bad idea to have an additional ration cupboard just in case.

This section is the longest of all, and will go over specific tips for how to stay safe in a few very unique scenarios, and contains the most spoilers out of any section herein, so be warned.

For the dry land habitat, you've very little to worry about, and should be fine (but pack your essentials anyway).
The second habitat is easy enough to get to, and you'll spend more time worrying about crabsnakes than actually fighting them, just don't get too close to any jellyshrooms. If it comes down to a fight, the stasis rifle found at the last habitat should be enough to keep you safe, but they are also deterred by melee hits.
The third and final habitat is a bit more tricky, because you're dealing with warpers and crabsquids. Make sure to park your seamoth a good 100-ish meters away from the base, and leave the lights off. This is extremely important, as crabsquids will decimate your seamoth if it's emitting light, leaving you without a source of breathable air, likely killing you. Keep a flare on your person here, as it will distract the squids should you need it.
Inside the ship there really isn't much to worry about, save a few bleeders in the engine room (so stock up on first aid kits and food). What you really have to worry about is the high concentration of Reaper Leviathans that prowl around the ship; being one of the few enemies that can one-shot your hardcore run. Approach the ship from its port (left) side with a cyclops, and park up in the shallows. Taking a seamoth the rest of the way in is recommended.
As long as you have a cyclops, you should be alright, regardless of where you're entering from. Avoiding the Ghost Leviathans in this area can prove extremely difficult, so it's recommended that you tough it out, and go to silent running/flank speed for as long as possible, and build a secondary base in the main fossil chamber, where no leviathan treads. This way, you can repair & recharge your submarine. Don't leave until you have discovered how to make polyaniline and can build yourself a shield. Thermal generators are recommended for keeping your base running, and you'll find no shortage of heat sources with which to power them.
This is definitely the section you'll have to worry the most about, because of the huge and terrifying leviathans that dwell in it, and the smaller, more abundant beasties that also dwell in it. Make sure to never leave your P.R.A.W.N suit while you're down here unless you absolutely have to, and make sure to wear a reinforced diving suit, because otherwise there's a good chance you'll boil and die quite quickly. Be extremely cautious when scouting the area, and only get your kyanite from the entrance to the zone, as to hopefully avoid the three Sea Dragon Leviathans. Small caves are your friend, keeping you out of the reach of these monstrous creatures, and the central alien generator is also free of the dragons. Don't forget to get the blue alien artifact from there either, and visit the surface through the portal to get supplies before heading back down. You also don't want to forget to craft a second artifact, as you'll need two but only get one. Lastly, don't try to fight the leviathans, just run, you can't beat them. [/spoilers]

Hardcore is just that, hardcore. It's extremely difficult, it can be extremely stressful, and it takes an extremely impressive amount of skill to complete masterfully, but with a bit of luck, and this guide, you just might get to the end of the game without dying. In summary, you always want to remember to:

• Have a backup plan
  
• Overstock, and always have resources at the ready
  
• Stock up on food & water, and carry a weapon wherever you go
  
• Be safe, not sorry
  
• Not die

And with that I wish you luck, and hope that you've enjoyed this steam guide on how to subvert the hardships of hardcore mode!