It is "released" under our license agreement which can be found at https://mocaponline.com/pages/standard-license. I would not describe it as Open Source. You should read it but the short answer is yes you can use it in your game...as long as " (ii) as part of a game if User Creative Work is displayed inside the game during play and cannot be extracted without use of reverse engineering techniques". I have made an assumption that you would qualify for the standard license but we also have a commercial license if your game "hit's it big" or you are building it as a work for hire for someone else. Our over all Licensing information is available at https://mocaponline.com/pages/legal. We also have customized Enterprise Agreements with larger organizations.