Very good idea, I had the same concept in my mind for a while, but you've pretty much nailed it.
I think it would be a good idea to have a massive maintanance complex running under all three main zones. The purposes of this zone would be:
- Providing shortcuts between the three main zones to make backtracking less tedious and discouraging.
- Escape routes from hazards such as MTF and sentient SCPs.
- Completion of crucial tasks that allow the player to progress (remote door control objective, clearing obstacles or creating chaos to clear a path).
- Some more SCPs and new hazards e.g: SCP-008 gas could be found leaking through pipes behind a quarantined section, closing SCP-008's canister will stop the infection spewing out of the pipes, allowing you to progress.
It shouldn't be possible to travel from the light containment zone to the office complex just through the tunnels right at the beginning of the game, rather the opposite should apply. At some point in the tunnels, there should be a heavy blast door preventing you going further, and you'd need to unlock it on the other side by progressing through the main facility and coming back round to the door. This makes the tunnels into a kind of unlockable shortcut that is useful for backtracking until all doors have been opened.
ey b0ss, can I habe de pussi plz?