In Katana Zero, you play as a samurai with only his sword to rely on. It’s the only weapon you’ll ever have, but it’s also the only one you need. At least until the end of the game, that is. After completing Katana Zero, you can unlock the Government Lab level, which in turn gives you access to five new swords, assuming you can find the keys to unlock them. Some of the swords you find this way give cool cosmetic changes to your blade, while others will affect how it works.
Before any of that, you have to first make sure you unlock the government lab. After you beat the game’s final boss, you’ll return to your therapist for one very eventful final session. Once you’ve finished your treatment for good, make sure to search both your therapist and his desk to get the key to the Government Lab, plus some other interesting information. From that point on, you can access the lab from the level select screen.
Unlock All Swords in Katana Zero
In the Government Lab, you’ll see five locked doors in the center of the room. There’s another door off to the right side, but that’s not accessible yet. To open the five doors in the center, you have to search some unorthodox places or complete challenges throughout the game.
The first key you can find is the Prism Key, and uncovering it is the very first thing you can do in the game. When the very first level starts, you’ll jump out of a window, kill a couple of guards, and jump down to a rooftop below you. When you first get control of your character, jump up to where you came from, onto the ledge to your left, and search the guard farthest from you.
This key unlocks the Prism Sword, which gives your weapon a cool rainbow skin and changes your victim’s blood splatter to a random color. Now you can paint the town red (and green, and yellow, and blue).
In the very next level, you can find the Master Key. Play the Hotel level through to the very end, when you reach this penthouse. As you move through, you’ll have to go through a door to the outside, then come back in. When you come in, there will be a statue on a podium that you can pick up. Grab it, but DON’T use it to take out an enemy. If you accidentally throw it, restart the level.
Just after this point, there will be a closed door to the balcony. Open this door by pressing against it, not by slashing it, then immediately throw the statue while moving to the right. You’ll kill the man standing on the edge of the balcony, and searching him will get you the key.
With the key, you can unlock Master Sword, which should sound familiar. Swinging this sword will shoot a beam of light that can take out enemies from a distance, but it needs a few seconds to charge between each shot.
This can be one of the easiest or one of the hardest keys to get, depending on how you play it. The easy way starts during your visit to your therapist. During this conversation, don’t interrupt your therapist or demand your medicine. Instead, insist that he answer your questions, and tell you that you spoke to Electrohead. Eventually, you’ll be able to say that you don’t want to take your medicine. Keep refusing to take it, and you’ll get a strange phone call during the mission proper. The voice on the other line tells you to kill everyone you come across. Do that, and you’ll get the Prototype Key when you return to your apartment.
The hard way is to complete the level with stealth. During your therapist’s visit, proceed as normal and take your medicine. You’ll get a phone call at the beginning of the mission reminding you not to kill anyone.
To get through the level without being seen, you’ll have to hide in the doorways in the first section to avoid being seen, and time your movements so that you’ll always stay out of the guards’ vision cones.
In the second section, pick up the bottle as soon as you enter the room, then stand on the stairs where no one on either floor can see you. When the guard on the bottom floor moves away, throw to bottle at the fire alarm to distract the guard on the top floor, then walk past him and into the other room. Use the stairway on this side to let the side guard pass over you, then move on.
In the third section, use the door when the guard is far enough away, then use the security camera feed to see when it’s safe to go back out and proceed.
The fourth section is by far the hardest, and there’s no perfect strategy for it. You need to stay behind the guards, move silently, and hide behind the workout equipment when you can. Be careful not to let the lights hit you as you move. Part of this section is just being lucky enough that the guard’s patrol patterns give you an opening to move, so it’ll probably take you a few tries to sneak past this part undetected. Once you do, you can collect your Prototype Key.
The Prototype Key unlocks a large claymore that can cut through enemy armor and deflect several shots in the same swing, making it especially useful for taking on riot officers with shotguns.
Getting the Phoenix Key is a breeze; it just takes some patience. Play through the Mansion level as normal until you reach a section with a burglar rifling through a room in the upper left corner of the screen. Go through this section as normal, taking out all of the enemies, but don’t enter the room with the burglar. Then stand by and watch him work. When the level timer is nearly up, he’ll make his escape. At that point, go to where he was standing, and you’ll find the Phoenix Key.
Using the Phoenix Key will get you the Phoenix Edge, a sword that blasts gout of flame out as you strike. It’s not as useful as the Claymore or Master Sword, but it sure looks cool.
The Savant Key is another tricky one to unlock. Not long into the Slaughterhouse level, you’ll come across a room with a cluster of monitors on the wall. As soon as you enter the room, jump and cut the wire connecting to the monitors. If the door slams shut and someone appears on the monitors, you were too slow and should restart.
From there, play the level normally until you reach a room with a stopped conveyor belt and cameras in the ceiling. Roll past both sets of cameras without being detected and keep progressing through the level.
When you come to another room with a cluster of monitors and cameras in the ceiling, again roll past the cameras without being seen. Remember that you can restart the section from the menu if you’re spotted. Once you get by unseen, drop down and go into the room to the left to pick up the Savant Key.
In the Government Lab, this will unlock the Savant Knife. Its attack area is much small than the standard katana, but you can swing it much more quickly. While it’s not the best weapon, you can jump into the air and swing it repeatedly to float for a good amount of time. Useful? Kind of. Fun? Definitely.
The final door in the Government Lab can’t be opened, but with DLC for Katana Zero already announced, that may be changing soon.