I'm not sure if you would call it "gaming", but I use twitter to get beta testers for all of my apps. If you have no money for marketing, it can be a great too

I'm not sure if you would call it "gaming", but I use twitter to get beta testers for all of my apps. If you have no money for marketing, it can be a great tool to get traction. The trick is to not act like a spammer and only try to target people that are in the demographic of your app.