Started building the behavioral tracking system — the part that reads what the player did last session and adjusts the facility around it. This is the core mechanic and I've been putting it off because it's the hardest thing in the game to get right.
The problem is subtlety. If the facility adapts too visibly, players feel cheated. If it adapts too quietly, they never notice and the whole concept evaporates. Right now I'm testing with camera placement — whether a corridor camera tilts slightly toward a path the player used last session. It's maybe two degrees. In playtesting I ran it myself and still couldn't tell if it was my imagination.
That's the target. The player should never be certain the building is watching them. They should only suspect it.