I've written a game that's a mix of algebra and maze solving. I believe its pretty relevant to this question. There are easy levels but also it can get surprisingly complex even for small mazes. Its called Numplussed and its free on Android or iOS:

https://itunes.apple.com/us/app/numplussed-number-puzzle-maz...

https://play.google.com/store/apps/details?id=com.codeulike....

Example of a hard level:

https://twitter.com/codeulikegames/status/911725658929291264

some easier ones:

https://twitter.com/codeulikegames/status/890246328290332672