At one time there was a Stanford course on the subject of General Game Players. The final project was to submit a player and see how it performed on a small set of games described by GDL. These were variations on Backgammon, Othello, and similar, with some rule changes.

While much of the course material survives [1], those rulesets do not. The only GDL example I could find was the somewhat trivial example of Tic Tac Toe, see section 2.6 Tic Tac Toe Game Rules here [2].

[1]. http://ggp.stanford.edu/public/lessons.php

[2]. http://ggp.stanford.edu/chapters/chapter_02.html

An email for Michael Genesereth, teacher of the course, is on the course website. I might shoot an e-mail and see if he has GDL files to share.