As you can see, there are a few ads on the site.
Those will be used for improving the site, paying current hosting for example or a more powerful one to reach new possibilities.
The money may also be used to pay for other projects, like linux games projects for example.

That will NEVER change : you will NEVER find ads on the wiki for free games, open source or not. Authors earn no or few money with their games, there is no reason for Games4Linux to earn any money from their work.