Sebastian has introduced me to Metrodle.
This is sort of like Wordle, but with tube lines. Basically you get a tiny snapshot of the tube map, with all station names and line colours removed, and you have to identify a highlighted station. As you submit incorrect attempts, it gives you successive clues - for example, it tells you how many stops away you are, and whether you're on the right line.
The extraordinary thing is that I have attempted it four times, and successfully completed it twice, using only memory and guesswork.Diamond Geezer putting it in my head this morning, but I'm taking full credit for Stratford being the only other station in the vicinity that I could even think of.
Now I know that there are people out there who will get it right first time, every time, but given how long it is since I used the tube, and how appalling my sense of direction is, I'm bloody impressed with myself.
Better not post this till midnight, in case you haven't done today's yet.