WildTangent Games is an aggregator of great games across the internet. They used to have a bad reputation, but now they're a model application. By earning the Compatible with Windows 7 Logo they've strengthened their commitment to privacy and security. With over 1300 games and 10 million new users per month, WildTangent is quickly growing in popularity.
WildTangent offers a few ways to enjoy your game: Free Trial (with advertising); Wildcoins to rent games; Purchase the full game.
The app itself gives an easy way to discover games in their enthusiast, casual, and family channels. They also have other popular channels so you can find the right game for you.