You're thinking of this:
http://www.graal.net/images/4/49/Graal_version_2_1_game.png (Unsupported image host)

There was a real offline singleplayer version back in the days. Back when Graal was called Graal: The Adventure. It's what the classic server is based on.

It even had a 4 player split screen offline mode at one point.
https://dl.dropboxusercontent.com/u/2531338/graalv1411.png (Unsupported image host)

https://dl.dropboxusercontent.com/u/2531338/graalv1411-2.png (Unsupported image host)

Update:
You could even save your progress if you played single player:
https://dl.dropboxusercontent.com/u/2531338/graalv1411-3.png (Unsupported image host)