A teaser engagement for Call of Duty: Ghosts has appeared on the franchise’s official site. An image is slowly being built on a new teaser page, populated based on Tweets using the #CallofDuty hashtag. The image appears to be taking the shape of the mask of Simon “Ghost” Riley, the British soldier last seen in Call of Duty: Modern Warfare 2.  Fans can click to post to Facebook or Twitter in order to be featured in the mosaic.