If you want to try playing regular expression Zendo against the computer, I have a JavaScript version here:
https://codewiz.org/~scubed/rezendo/rezendo.html
That way you can get immediate feedback.
I have made a version of Zendo also. This one uses regular expressions (like what darius mentioned). It's just JS, so it doesn't have any special prerequisites to play.
If you want to try playing regular expression Zendo against the computer, I have a JavaScript version here:
https://codewiz.org/~scubed/rezendo/rezendo.html
That way you can get immediate feedback.