Noticed by Siliconera, the patent proposes offering "most or all of the full version of the game" for free, then slowly "eroding" the demo's functionality in the hopes of enticing a purchase. For example, a sword that grows smaller over time or a racing game where tracks can only be played a certain amount of times unless purchased.
The crux of the patent revolves around the idea that current demos often fail to provide an overall feel for the game, and instead focus on one particular aspect:
Typically, the demonstration version of the software does not permit the gamers to have a true experience of the full version of the software that the demonstration version is promoting. Demonstration versions typically permit the user to play only a small subset of the play characteristics of the full version of the video game. In this way, it fails to provide gamers with a more complete experience of the actual video game and, as such, does not fully and accurately promote the video game.
It may be desirable to implement demonstration versions of video games in a manner that more fully promotes the features or characteristics of the game while still providing protections that will induce gamers to purchase the right to use the video game.