Hexolab's "A Car's Life" game

From Labnol.org:

Sometime back Google introduced video annotations in YouTube that can either be plain text appearing over the video or they can be links which point to other videos hosted on YouTube.

Now this may seem limiting because you cannot link to external content from YouTube videos but Hexolabs, a mobile game development company, found a creative use for annotations.

They have developed a very basic but probably the first video game for YouTube using just the annotations feature. Called "A Car’s life" you can play this YouTube game here.