I created this game using a game engine called impactjs. The game is primarily coded using JavaScript, I have uploaded some of the code I used to create the boulders, bullets, player and the main JavaScript function which spawns the different entities and screens.

I calculate the scoring system by taking into considerating the users time, kills and deaths. I then use PHP to submit the scores to a MySQL database. The scores can be viewed on the leaderboard page.

If you have any more ideas or feedback please contact me.