I love these type of games but this one is done very lazily: as for audio why don't you have a chime when the draw starts, and maybe some suspenseful music while the timer runs out and some screams or something so we know when the other guys dead. Secondly for visual you should add in blood effects, and gun smoke. Thirdly for good measure add custom characters and (if you're up to it) custom guns. Lastley if you bring multiplayer to the game after following the rest of the instructions it will be the most played western on this site easily.
Someone else asked for using numbers. R will be for chambering new rounds with bolt action rifles.