OH! I have now a great analogy! I guess you know how a firewall works (the very basics, I mean, I dunno much about it), so it could be that the gaps between the bullets are open ports where you have to find your way trough. There can be separate firewalls on a single connection and between each device so the "overworld" makes sense as well. As for the timer - it could be a password which is being figured out by brute-force (the technically easiest method of hacking where the attacker tries every possible password until they find the right one) and the more devices you've taken over the faster the password is figured out.