Commit e0e0e7aee165bedaa2e9b55fd75a23ad45c4ecc8 removed the mansion's doors to avoid a "lighting bug". However, I don't think any bug that's just a visual bug is worth removing the mansion's doors. The doors are essential:

-Removing them makes the aliens quickly find their way to the civilians, the player can do near to nothing to help due to being out of range/inability to function as a replacement target. Due to how the map is built, it takes quite some turns to get to the aliens. The map is changed from one where most or even all of the civies tend to survive into one where almost non survive, just by removing the doors.

-The doors are what makes this map so nice and pretty special (I once ranted about the map, but my view has changed). Such as the decision whether to risk that an alien comes through the next door and stay in reaction fire position, or rather move to the door, have a look behind and close it again. After killing an alien or not, hoping it won't open the door its next turn. If there is an alien behind, that is.

-I reverted that commit and kept playing with the "lighting bug"; I noticed something but it wasn't particularly disturbing (as opposed to the lack of doors).

So please re-add the doors.