I just finished two runs on Maximum Security. I played my first run completely blind. Since I missed a few collectibles, I had to do a second playthrough just to get the "Grim Reaper" achievement. The second run was a lot smoother since I knew what to expect, i.e. where the jumpscares were, where the checkpoints triggered, where the crafting forges were, and when a boss or a really hard encounter was coming up.

During this run I've been gathering quite a bit of information on Reddit as well, especially when it comes to loadout building.

So I'm sharing here everything I've learned. This should be useful for those who are new to the game, as well as those who are familiar with the game mechanics.

1) WEAPON QUICKSWAP ONLY HAPPENS WHEN YOU HAVE BOTH LONG ARM AND SIDEARM FRAMES.

Jacob has two guns on his person from the middle of Chapter 5 ("Lost") onwards: a long arm and a sidearm. For the sidearm, you have the Hand Cannon, the Tactical Pistol, and the Skunk Gun as options. For the long arm, you can only choose between the Riot Gun and the Assault Rifle.

Switching from sidearm to long arm is quick and easy. Jacob holsters one gun and whips out the other. Self-explanatory.

Why am I explaining this? This is because you get access to the Skunk Gun not long after you get the Hand Cannon, in the "Aftermath" chapter. (If you miss it, you'lll have another chance to get the schematic at the Oxygen Processing Facility near the end of Habitat.) A lot of people were complaining about the slow and very inconvenient process in swapping between the Skunk and the Hand Cannon, and it got to the extent that the devs sped up the animation just to accommodate them.

This is because that the two guns share frames. To switch to another gun on the same frame, you have to hit the weapon select button, scroll your middle mouse up or down, and confirm it. Jacob will then manually change the parts. It's a lengthy animation, and you won't have much room to change weapons in the middle of combat.

Keep note of that as you play.

2) YOU HAVE LIMITED CREDITS. FOCUS YOUR UPGRADES, DON'T SPREAD THEM OUT.

There aren't enough credits to upgrade everything in a single playthrough. I ended my second run with the following:

• Baton: LV2 left and right branches (block breaker, combo extender, heavy attack, and damage boost LV1)
  
• GRP: LV2 recharge, LV3 energy cap, LV3 throw damage
  
• Skunk Gun: ammo capacity, stability, increased damage
  
• Assault Rifle: fully upgraded

That is equivalent to 27,200 credits and I got to the final boss with a spare 800 to 1000 to buy extra ammo with. A significant amount came from my decision to specialize in as few weapons as possible and selling nearly every health injector I picked up.

Don't spread yourself too thin purchasing more weapons than needed. Work with the gear that work best for your playstyle and stick to it.

3) GET THE BLOCK BREAKER ON THE BATON ASAP.

This should be your priority as soon as you get the Stun Baton as well as access to the Reforge. It's annoying when you're in the middle of your melee combo and the opponent just blocks your attack and forces you back into the dodging routine.

The block breaker basically removes an arm whenever the opponent tries to block your strikes. You are able to continue your combo for another couple of hits and better yet, you disable the enemy's ability to make continuous swipes at you. An enemy with a broken arm or a missing head can only attack once, making dodging ridiculously easy.

You will need a total of 1200 credits to get the Block Breaker and its prerequisite upgrade.

4) THE TACTICAL PISTOL IS WEAK.

Self-explanatory.

I never bought the tactical pistol, but I've seen several videos on it and it has been discussed on Reddit. From what I can see, it's very underwhelming and will just be a waste of credits. It also dilutes your loot pool, and if you already have the Skunk Gun unlocked, it will just make Hand Cannon or Skunk Gun ammo drops rarer.

You can find the schematic in Chapter 6 ("Below"), in one of the side rooms before arriving at the very first Reforge in the chapter. It's kinda disappointing at how weak it is compared to the other guns you'll have by this point in the game.

5) THE OTHER GUNS ARE VIABLE.

Having used the other weapons myself, they are all viable for the rest of the game.

However, I will not recommend the Riot Gun. I've found it to be the weakest of them all, even weaker than the Skunk Gun (a shotgun that shares frames with the Hand Cannon). The only benefit to the Riot Gun is that it reaches max upgrade sans alt-fire with just 600 credits. Even so, the difference in firepower compared to the Skunk Gun is very noticeable.

6) THE GRP DOESN'T PARTIALLY RECHARGE.

The GRP is an extremely powerful tool in your arsenal. Its mere existence can trivialize certain encounters in the game, allowing you to yeet all non-boss enemies into environmental hazards or out-of-bounds to kill them instantly.

With how powerful GRP is, it is balanced in three ways.

• GRP batteries cannot be crafted.
  
• GRP batteries occupy one inventory slot each.
  
• Contrary to the tutorial's own phrasing, the GRP energy does NOT recharge partially over time.

That last point needs to be stressed.

When you use GRP, you consume a set amount of energy depending on what you are targeting. As soon as energy is consumed, the game starts a timer in the background. Once the timer reaches zero, the GRP automatically recovers 100% of its energy all at once.

I don't think the timer is reset when you use GRP while it's on, but it still gets paused and just delays the recovery even more.

As an FYI, with no upgrades to the recharge, the timer is set to 3 full minutes. This number goes down by 30 seconds with every recharge upgrade, culminating at a 90-second timer for max level recharge.

7) THROW ENEMIES ON TOP OF PATHLESS OBSTACLES TO KILL THEM INSTANTLY.

You don't have to throw enemies out of the arena or into environmental hazards.

You can also launch them onto beds, a pile of barrels, a high stack of boxes, or things that the game ai cannot calculate pathways with. The game will also consider these as out-of-bounds and instantly kill the enemy... while ensuring you have access to the corpse to loot it.

It's laughable and cheap, sure, but if you're on Max Security, you're low on ammo, low on health, and you got four enemies rushing your position, you won't be picky with your options.

8) WALL SPIKES HAVE UNLIMITED USE.

If you launch an enemy into spikes with the GRP, their corpse will just hang there. This might mislead you into thinking that you can't launch another enemy into the same exact spot.

In reality, you can.

Doing so will just dislodge the first corpse and replace them with the second one. What might get messy will be the loot spawning. Jacob tends to stomp on the wrong things once this happens, at least from my experience.

9) AMMO ONLY DROPS FOR THE WEAPONS YOU'VE ALREADY PRINTED.

Do not print weapons you have no intentions of using.

This will dilute the RNG pool for enemy drops or random loot. Ammunition for the other weapons only start dropping once you've printed them. So if you end up printing a new gun and you don't like it, even if you don't use it the game will STILL give you ammo for it.

Because you are not able to sell weapons, your only recourse is to reload a previous save to undo the print.

Take note that the extra ammo on unwanted weapons isn't necessarily a bad thing since you can still sell them. However, it occupies precious inventory space and it'll suck if you NEED ammo for a specific weapon you're favoring but the game's RNG is working against you and you are unable to backtrack to the nearest reforge to print more ammo.

10) DO A MANUAL SAVE AT THE START OF EVERY CHAPTER.

If you are keen on getting all the collectibles, you'll have to do this. Some are easily missable, and worse, the game doesn't allow backtracking and it doesn't have "chapter select". I had to restart my second run 5 hours into it because of this, and I didn't have a manual save at the start of the chapter to save time.

11) MANUAL SAVES ONLY SAVES THE MOST RECENT CHECKPOINT.

Manual saves in Callisto Protocol do not save your current position in-game and all the items that you have spawned but not collected. Do not make the mistake that many others have.

As of December 26, 2022, manual saves only make the most recent checkpoint permanently available as a load option.

12) RELOADING THE CHECKPOINT MAKES ITEMS DISAPPEAR.

If you're managing excess inventory by picking up items and dropping them in places, and you intend to pick them up later once you freed up your inventory by selling the fodder at a reforge station, do not reload the checkpoint as much as possible.

From my experience, reloading the checkpoint makes these items disappear or become uncollectible. Lugging an extra 3 health injectors and 2 energy converters? Better not die or reload the checkpoint, or you can kiss the extra 500 credits goodbye.

This also affects items that you have already spawned simply by entering the area -- like Pristine Energy Converters (200 credits) or Decoders (500 credits). Reload by dying or manually choosing the option on the pause menu, and those disappear too! If you want them to stick with you, they need to be in your inventory when you trigger the next checkpoint.

13) KEEP YOUR HEALTH UP AS MUCH AS POSSIBLE.

The game also shows bias in its RNG pool.

When you are low on health, the game will assign a higher probability of spawning a health gel. While this is all well and good, health gels cannot be collected, not to mention that ammo or credits could've spawned in its place instead.

Ammo is expensive in this game: 70 for 2 Skunk Gun rounds, 140 for 4 Riot Gun rounds, 140 for 20 AR rounds, and 120 for 6 Hand Cannon rounds. You already have a fairly limited amount of credits, while there are PLENTY of health injectors to pick up, and they all sell for 100 credits each. Using up a few to save on ammo costs won't hurt much.

It is also worth noting that, on Maximum Security, Jacob goes down in very few hits. You don't want to suddenly get one-shotted by an enemy that catches you off-guard.

14) DON'T SHOOT ENEMIES WHILE THEY'RE MUTATING.

Tentacles sprouted out of an enemy's chest and you failed to put them down in time? Then wait for the animation to finish. Don't unload on them while they're in the middle of mutating.

From my experience, shooting them at this point just wastes ammo. Let them have their little moment. They can't attack you while that's happening, so you have a few seconds to focus on other enemies. Once they're all set and got tentacles for arms, shoot to kill.

Another option to deal with enemies in the middle of mutation: launch them out of bounds or into spinning blades with the GRP. Instant death.

15) CARRY ONE OR TWO GRP BATTERIES AT ALL TIMES.

With how powerful the GRP is and how scarce its energy is, you will want to carry around 1 - 2 batteries at all times. There are so many enemies that you can easily run out of energy, and if they swarm you, it will become difficult to manage without getting hit especially if you are conserving ammo.

You won't need more than this much except in a few encounters where you'll have multiple enemies rushing at you, but the game would be dropping all sorts of goodies on you prior to those, so you should be well prepared by the time you get into it.

16) STEALTH KILLS AND STOMPS ARE ALL SILENT.

All stealth kills and the stomping you make to recover loot from bodies are silent.

Yes. You don't break stealth despite the fact these things sound VERY loud on your speakers. For whatever reason, the devs made sure it doesn't trigger aggro... even if it kinda breaks the immersion.

17) DON'T BE INTIMIDATED BY THE BLIND ENEMIES.

The blind enemies that are introduced in Chapter 6 ("Below") can be intimidating. They are tankier than the usual enemy, and when you alert one, you alert all of them and they can easily swarm your location.

The funny thing is, you can easily dispatch them while they haven't gotten out of their cocoons/resting places yet. Approach them silently, and when you get close, whip out your baton and whack them once. 70% of the time they would spawn only to flop over and die.

There will also be segments in Chapters 6 and 7 where they'll be meandering the area and you either have to sneak past them or perform stealth kills. You can get surprisingly close to them without triggering aggro, so don't start backing away just because they're approaching your position. I've gotten up really close to them a few times, crouch-walking around just to get to that angle where I could whip out a stealth kill.

18) YOU CAN GRAB DORMANT ENEMIES.

All enemies that are dormant and just waiting for you to approach them and trigger their aggro can be picked up by the GRP.

There are only a handful of places throughout the game where a corpse will just suddenly rise up and start smacking your face. These are mainly one or two enemy encounters that are easy to manage with upgraded weapons.

However, there is a section in "Lost" where you can encounter up to 7 enemies hiding in plain sight. The GRP will pull those that are laying dormant and bring them over into melee distance.

The only exception to this would be the blind enemies, which do not become active until you make noise or hit them with a baton (and they survive that RNG mentioned in the previous point).

And that's it! I hope you guys will find my tips useful.

Don't forget that you can find more useful information on the Callisto Protocol subreddit! I've found plenty of information on there, and they helped with my first (blind) Maximum Security run.