There aren't many choices for HTML5 in game ad networks. Google has a program, but it requires a lot of traffic before you can use it. That's how just about all in game advertisers that work on the web will be. All reliable ad networks will require that you have control of the server it will be placed on.
That being said, there's no reason you can't place normal ads on the same page as a game, although most networks will have specific rules for placement.
Keep in mind that normal ads require cookies, and page content to serve viable ads. If you don't have content that can be parsed and useful to advertisers, then don't expect great ad revenue.