c4countdown

As Gavin's revisiting puzzles

Anyone done nandgame?

https://nandgame.com/

Did it years ago, but looks like they added some further steps since I completed it.

Challenging but logical, educational and fun! (YMMV)

Interesting.

(My motivation is that I've been tying up loose ends - things that have been at the back of my mind to do for years. I've restarted work on my novel now as well.)