It would be fantastic if someone could make this plugin...
In each level, after 25% of the chapter passes, the survivors will receive a password number for 10 seconds on the screen. After 50% of the map passes, they receive another password number, and so on 75% and 100%
In total there would be 4 passwords, at the end the survivors must write for example. !1234 to open the security room door, the password is (25%50%75%100%) <--- numbers given in order. Survivors will get 3 attempts. If 3 attempts are incorrect, they will have 1 minute to hold off hordes and special infected, after that time the door will open for 20 seconds, those who are outside the shelter after that time will be killed.
It would be interesting if a plugin like that existed...
Linear Mode
