Did a few google searches on this, but not to my surprise, only results about video gaming come up. 

In Hamlet, Reynaldo says: "As **gaming**, my lord." 
to which Polonius replies "Ay, or drinking, fencing, swearing, Quarreling, drabbing—you may go so far" 

or to describe Germans, British lexicographer Sir William Smith writes: “Their men found their chief delight in the perils and excitement of war. In peace they passed their lives in listless indolence, only varied by deep **gaming** and excessive drinking.”

I'm guessing it means something along the lines of having fun, but is there a more specific definition that anyone knows?