Pls tell me how can insert ads in game like here www.best-arcade-games.net/game/48/HotCorn.html ...and if is not illegal.
You can experiment using a link unit on the left of the site. Add in a box or rectangle ads above the game frame and track the results. You can also put a ad unit below the game frame.
Just try not to place the ads too close to images or buttons. Somewhere at the top or on your left column should help.