Copter was built and published without the source code files. The developer choose not to release its source files and there is no way to try and modify it using traditional ways. Although you can buy the game and ask for source codes, that will most likely won't happen. Trying to code it by yourself (in case you don't know J2ME) is a little hard because your don't know the algorithms of the game or how it's running. You can try to make a clone, but original algorithms of coding are known only by the developer. To make it short, you can't get the source code files for this game.