I find that YPN works great on gaming sites, because you can target ads about electronics and what-not rather than Gaming ads (which are usually sites selling MMORPG Gold and crap like that)
Well, I'm running over 15 gaming sites right now, so I'm using quite a few different categories: Electronics and Appliances / Consumer Electronics Computing / Computer Hardware Electronics and Appliances / Professional Entertainment Electronics Electronics and Appliances / Business Telecomm Equipment -- The first two are best for CTR on gaming sites, the bottom two are best for high cost per click. But of course, there are so many different types of "gaming" websites with such a big range of age groups in visitors and stuff like that, so you'll have to test that out yourself. (The majority age groups on my sites are 13-19)
Ads arent a relevant of adsense but overall i think it comes out ahead with larger cpc. Im getting around $5 per 1,000 page hits so it is alot better then google which i was getting around $1.
Thus far YPN's penchant for hosting higher-paying ads with less relevance has made for MUCH better payouts than AdSense. You should definately try it out. If nothing else, put it in rotation and see how it goes.