This video shows you the whole gameplay of how to get the 10 purple key cards for the optional side mission.
(Don't mind my bad editing)
Purple card locations:
1. At the secret room accessed only with the 3 golden key cards with all the legendary weapons.
2. At the top left-hand corner of the big room next to Stage 2. Go to Stage 2 and enter the hallway at the top that does not say "Stage 2." That is where the room should be.
3. At the top room above the bridge. When you spawn at the bridge, go up and you will enter the top room, which has Med packs and Shield cans. Then the card should be on the bottom right corner.
4. At the bottom of a dead-end near the library. At the hallway leading to the library, there should be 4 mobs continually spawning (making a square) at the opening leading to the library. There also should be two short hallways (that lead nowhere) at the top and bottom of the hallway. The key card should be in the bottom one.
5. At the final laser room that has a black floor and LOTS of lasers. After the second laser room, you meet the next laser room (where I died multiple times). Go to the top left corner and the 5th purple card should be there.
6. At the room below the bridge that is big and spacious. When you spawn at the bridge, go down and you will enter the bottom room, which seems to be filled with junk and beds(?). When you are there, go to the bottom right corner and that is where the card is. There also is a computer next to it that has some information on it that you can read!
7. At the red (or red velvet) hallway below the kitchen. Go to the kitchen, and head down into the dark red hallway. There should be a short hallway at the bottom with a mob inside. That is where the 7th purple key card is.
8. At the laser room after the library. Go to the library, and then go to the laser room on the right. At the last laser, there should be a purple key card inside. Well, the key card is inside the laser, so you have to carefully get it out without getting zapped! DO NOT GET IT WHEN THE LASER DISAPPEARS!!! The laser only disappears for around 3 seconds, so if you get the key card when the laser disappears, you will be zapped. Instead, cross the laser and get the key card on the other side from the top.
9. At the big room next to stage 3. Go to stage three, and then head left into the big room. The purple key card should be located in the middle of the room, partially hidden by a box.
10. At the very end of the escape room. Go past the final laser room and into the escape room. Make sure NOBODY BREAKS THE BIG BARRIER, or you will lose your progress (this happened to me). Go to the space suits. The purple key card should be located in one of the empty suit holders.
After that, go fight the boss!
I would HIGHLY recommend that you get the legendary evil eye at the first purple key card room and a friend. Fighting the boss will be much easier!
And this takes quite a lot of time to complete, so have around 1 hour of spare time on hand!
Have fun!
