According to an internal email seen by The Wall Street Journal (via Reuters) YouTube is internally testing a new feature called Playables. In summary, it gives its users access to a selection of video games, both on mobile and computer.
Voice over to YouTube
Among the games available for this test, some titles from the Google PlayStore like Stack Bounce (photo below), which can run both on the YouTube site on an internet browser, and on the iOS or Android smartphone application. Questioned by the Wall Street Journal on this subject, YouTube replied by the voice of a spokesperson: “Gaming has always been a center of interest for YouTube. We're constantly experimenting with new features, but have nothing to announce at this time."