Playing with FGU 4.5 layers in 2d and 3d

2 videos, same action on the Alien ruleset 2D then 3D.
Entering a 2 floors compound. no enemy. only one map, no "portal" extension.
https://www.youtube.com/watch?v=906qhSRbANA
https://www.youtube.com/watch?v=O7pmEXvNZSQ&

Very cool videos, and I dig the idea of stacking maps. Can you elaborate on how you managed to stack and reveal different LOS? I might have missed that feature.

I use multiple layers. In this case one walls/lights layer for the 1st floor and another walls/lights layer for the 2nd floor.
Show, don't Tell, they say:
https://www.youtube.com/watch?v=2BFDNWYdM3E
You will see in this video what I have done, layer by layer.
This method is interesting for a little map. For large maps it is better to use the "portal" extension you'll find in the Forge.
Note that there is some lights leaking outside walls. I have to move them everytime I reopen the map.
I don't know why. I must do more tests to see if it is a bug and if it is interesting to report it.