I was more thinking of some types of toilet cubicle door locks that when the bolt is shut the outside part of the lock shows "Engaged".
I have had to take a break as all the reading is starting to give me a headache from eye strain. I suffer from optically triggered migraines (eg going from very bright surroundings to dark or visa versa) occasionally, so want to avoid that.
After absorbing as much FW as I could handle, I had a quick shuffle through the Tactical Playing Cards. When they were proposed I was fairly sceptical, especially for a solo player, as I didn't want ASL to end up like a CDG or Magic The Gathering. However after looking at a fair few of the cards, I have revised my opinion. Though the accompanying sheet gives instructions for two players and any "poker play" would require two players, I can see a use in solo play.
Something on the lines of draw one card at random at the start of a player's turn and use (and immediately discard when used) or not as that player sees fit and discard regardless at the beginning of that player's next turn. Maybe two for really big scenarios. While not really counteracting a solo players omniscience their use would add some quirkiness or unique flavour. Whether I will use them much, I don't know but my view is now fairly positive.
Oh, I almost forgot, I think their physical quality is very good.