Pentagame online by Mike Ziebeck, beta:
You can play Pentagame against Ai Ai, Stephen Taverner's outstanding abstract boad game AI. Download it.
This requires installed Java and may have to select "Pentagame" in the list of over 170 games.
This has also generated statistics and general information about Pentagame:
My Github is https://github.com/penta-jan/
There, you can find a lot of stuff. And add your own language to the rule collection if you are wise :)