The biggest problem with using copies of a level for this sort of idea is that unless you can know at every staircase which rooms have and have not been conquered, things will not always be set up consistently when the player returns to old rooms after crossing a plot staircase. Maybe that's not a problem for this hold, but it could be in general. I'd imagine trying to keep changes synched during development would be annoying too.
There are three ways the same room can behave differently when the player enters multiple times:
1. The room has or has not been conquered.
2. The player comes in by a different entrance.
3. An NPC has exited the room permanently.
Stefan already demonstrated a way of using #1 to connect plot across rooms. But as was noted, that method can only put the room in two states, and so it can only test for completion of one task. My attached hold shows how it might be done with #2 or #3, requiring two independent tasks to be completed in each case.
Head east, and see how room entrances can keep track of the tasks. The drawbacks here are obvious: It's ugly (an NPC to strike the orbs might make the exits a bit smaller, but not much) and time-consuming for the architect. In addition, the multiple entrances must be in place in
every room the player might visit between accomplishing the first task and the final goal, or the information will be lost. If you go back to the Entrance of my example hold before defeating 2E, you'll need to start the entire east section over again.
West of the Entrance, I used NPCs to get 2W to remember which tasks have been completed. I really like that method.
It occurs to me now that the NPC method could be done even more transparently, so that the player can't even see a difference in the room (unlike the disappearance of the seep characters in my example). For example, with two tasks again, set up three characters:
Click here to view the secret text
×
A
(not necessarily visible):
If ... go to "Task X"
Wait while NPC at <location of B>
If ... go to "Task Y only"
Wait while NPC at <location of C>
Go to "Neither task"
Label "Task X"
If ... go to "Both tasks"
Wait while NPC at <location of C>
Go to "Task X only"
Label "Neither task"
<...>
Label "Task X only"
<...>
Label "Task Y only"
<...>
Label "Both tasks"
<...>
B
(initially visible):
Disappear
<If task X is complete, this script should End>
C
(initially visible):
Disappear
<If task Y is complete, this script should End>
Make sure A comes before B and C in the monster move order.
Secret tag is not really a secret, just a bit long.
Also, I had way too much fun designing this silly hold.