Wikipedia
GEFS-Online
GEFS-Online is a free, online flight simulator based on the Cesium plug-in (formerly the Google Earth plug-in). and provides a multi-player environment for players to interact with each other through the chat function. Created by Xavier Tassin, it was launched in October 2010. GEFS-Online has since expanded rapidly, with an average of 100 players on at any one time as of August 2013. On September 1, 2015, support for the Google Earth plugin and other NPAPI plugins ended on Google Chrome and soon after other browsers, nearly resulting in the shutdown of GEFS-Online. In January 2016, in light of the Google Earth plugin's termination, GEFS-Online migrated to Cesium, an open source 3D globe platform.