Cocos2d-js game clone with few alterations to make new game

Game should be a copy of an existing game that we have all the source code for which can be provided to be used as a base. Existing game has been created in cocos2d-js using cocos studio. All images and sound files will be provided for new game. Small change is required to bonus game logic to make it a slightly different game. The back end system is already in place, the new game should work with the back end system just like the original game does but it should use its own name so its another game within the system. Specific technologies required: cocos2d-js Extra notes: All code to be stored in a bitbucket repo. All game code, game design and rights of remain ours and should not be used anywhere else.