Kongregate

Online gaming community and directory for online games. Hosts thousands of user-contributed and rated games to choose from. Not only it provides a platform to productively kill your office hours but also a nice atmosphere to socialize with like-minded people.

Features

• Browse games by: Latest games, Highest Rated, or by category (Action, Racing, Shooter, Sports, Puzzle, etc.)
• Get privileges by earning points. You can earn points by uploading games, rating games, completing achievements, and inviting new friends. More details.