I wrote a blog post about this project.
cabal run zendoeval will build and run the game. The available commands
build [koan], guess [rule], and end (give up). Koans are printed and
input using an abbreviated format:
r3 -- a large red pyramid
r3b1 -- a large red with a small blue on top
r3b1 b3g2y1 -- two adjacent and touching stacks
g2> y1 -- a medium green pointing at and touching a small yellow
g2> | y1 -- a medium green pointing at but not touching a small yellow
For information about how to write rules, see my other blog post about how to write Zendo rules in Lojban.