Increasing your Clearance Level is required if you want to open all the secret security doors. This guide tells you How To Get Clearance Level 1 Card In Control so you can increase your Clearance Level to one and open the doors that require that level of clearance.
At any point you can open the menu and navigate to the Assets tab. This shows you both your current Materials and your Clearance Level rank. When you first start the game, you do not have any level of clearance so you are unable to access any doors that are behind Clearance Level locks.
How To Get Clearance Level 1 Card In Control
To obtain the first key card and reach Clearance Level 1, follow the main story until you reach the second mission. This is when you are tasked with going to the Mail Room so you can pass through to reach the Secure Line.
The entrance to the Mail Room is locked behind a Clearance Level 1 security lock. Nearby, there is a dead guard on the floor. If you search the item near his body you will find the first card and increase your Clearance Level to 1. Once you have this one, you’ll want Clearance Level 2.