Matthew Martin#CodingKata implement the frogputer
https://www.smbc-comics.com/comic/2012-12-21
Has frogs, boxes and flies. I'm a bit fuzzy on how it works. Trinary? 3 states? But frogs can eat the flies. Also frogs and flies persist after you remove them from the box, so 0s are free but you got a limited number of frogs and flies (1's and 2's)