The selling of space for advertisement in a game is one means of generating income that can be done by free software games. It is most typically done with web-based games, by selling a small segment of screen space around the game's interface. It could also be done through server-side games, wherein advertisements are actively placed within the game environment as wall textures or billboards. It could even be done client-side, although the free nature of the code would probably lead to the release of advertisement free forks. This system of revenue generation has been recommended by Charles Goodwin of Free Gamer, in comparison to asking for donations or offering premium content.