Please wait a second after clicking the stop button to let the project detect that you're done. Otherwise it will still think you're on and no one will be able to play if both players do this. If it doesn't work that's probably what happened.
THIS IS JUST A TEST Using a cloud list engine by @Lirex Engine: https://scratch.mit.edu/projects/22003344/ - - -| Changelog |- - - - - -|9-20-16 |- - - - C changes tank. - Shrunk arena. - Removed pentagon nest and crashers.