[1] https://github.com/rochus-keller/Luon/blob/master/Readme.md [2] https://news.ycombinator.com/item?id=42413343
If you like this, check out https://betweenle.com.
Betweenle is based on the same game logic, but gives you very useful visual clues along the way.
There were only a few times (maybe 2 or 3 in all that time) when I saw some messages indicating that something was wrong with the battery (though they never were as frequent as in the author's case). In each of those cases, the messages went away after replacing the battery.
(If you check my HN post history you'll see I post a lot about Haskell. That's right, part of Groq's compilation pipeline is written in Haskell!)