By activating the security protocol, you will launch the hard mode where brand new and more powerful enemies are already waiting for you as well as the opportunity to obtain special reward. We highly advise you to prepare thoroughly for looting the bunker and avoid going there with pickaxes, shovels and devastators. In order to gain access to the new mode you will have to find the army specialist. Pay attention - if you activate a security protocol, you will not be able to get back to normal difficulty until the bunker is restarted!