flash actionscript:

It will depend on how you have the game developed. If everything is based on
the playhead moving from frame to frame then you could just do movieClip.stop();

But since you created a game, I'm assuming that this would be too trivial of
an answer. Without more info all I can say is that you should create a _root
level function that stops all current animations, movieclip playheads, sounds,
etc. Depending on the complexity of your game this could be a lot of stuff.

Tim