Ran into two situations yesterday that raised the following questions about cards that attach themselves to rooms in The Complex.
First question. Can the cards that attach to Complex rooms stack on top of one another? There are event cards in the Aliens scenario that attach to the room they were discovered in. These cards double the cost of scanning those rooms until completing the current objective. We ended up having two events discovered in Med Lab and didn't know if they stacked. We just stacked them and played that way because we couldn't find any rule that said not to. It increased the cost of Med Lab scanning to 8 (doubled the base value of 2, then doubled it again).
Second question. Unless stated otherwise, do attached cards stick around after the current objective is completed? One of the Aliens objective cards states that the event cards which increase the cost of scanning go away once you complete the current objective. But what about the sentry gun cards which also attach to rooms in the complex? Nothing says they go away when completing their objective so we just left them attached to the rooms until the end of the game.