10 is not a lot, as long as they are good quality games that people play you should be good to at least 30 or so. If you find yourself loading games just for the sake of having more and end up with 100+ like some sites have, then I think it is too much. But a good selection, "good" being the key word, is a good thing.
It's not going to effect your site on a technical level though, just want to keep a good signal to noise ratio