Hello...
Come on, maybe u do not have to worry about how to put adsense banner as it is rather well known, but it is a matter of profit to be desired in the case of games would be better admob but also around another headache for developers who do not have much knowledge in programming.
One way I tested it and came to work is to use another source of advertising is an example ad.fly where u can create your own banner with a link to download another game or your application.
he comes to yield around $ 5.00 per 1000 views depending on your country.
Steps.
1 - Create an image advertising or gif up, and put the url for the link your account ad.fly, place in a good spot in your game type after spending a screen or to get into the game.
2 - Put a function that clicking the link will open up another page out of the game, no need to leave the game and ready.
If you stop and think of any way by opening the link adsense or admob one web page will open, in that case u will be doing advertising for their games and profiting at the same time.
A good option
note: There are other tools out ad.fly that can be used as banner for monetization that's just one example.