Initially when I was doing research on phonegap I came across a site that said there are many gaming app powered only bu javascript.So yes,Its possible to create a gaming app with phonegap
So here are few link that you might find useful
http://phonegap.com/blog/2013/01/18/my-first-mobile-game-in-html-with-phonegap-build/
http://www.tricedesigns.com/2013/03/22/phonegap-legends-a-sample-game-app/