Note: At this point ISSS is not accessible Edit
ISSS is a mob arena created by DeathKnight1003, TheJ_Team, and Koffee7. In the arena the player fights through the International Silver Springs Station (ISSS) to earn credits. Then players can use credits to unlock doors to open up more of the arena. Eventually players can reach the S.I.M.B.A. power core beacon in the center of the base to upgrade their gear for credits.
There are 4 classes: Engineer, Janitor, Security, and Scientist.
The engineer class is a strong supporting and damage class able to wipe out large amounts of mobs easily.
The janitor class is weak in damage and health, but is able to support very well.
The security class is a tank-dps class that can take a few more hits than other classes.
The scientist is a very high dps but low defense class able to wipe out zombies easily.