Logic 90 in the template game (and hence games that are based on the template game) handles non-room specific game functions - things like the player asking to examine items that they have in their inventory (e.g. typing "look keycard" and being shown a close-up view of the keycard along with a description). There are also responses to inputs like "get <something>" and "look <something>" that haven't yet been parsed by other logics (in each interpreter cycle, logic 90 is always called AFTER the room's logic), so for example if the player is in a forest and types "get remote control" they'll get a response like "You can't get that here!" because there is no remote control in the forest, and hence that input hasn't been parsed (responded to) by the room's logic.