It’s not bad for a simple shooter game. It reminds me of some basic Flash games I used to play back in the days when MiniClip, Armor Games, and Newgrounds were big on that sort of thing. It’s quite rudimentary, but it shows that you did take some time to put something together, as I don’t recognize those assets from any other game I’ve run across.
It’s very unfortunate that you can’t make it work without linking to an external website, which is why I subtracted a star from “Ease of Playability”. While the game itself is easy enough, I would think most people don’t want to have to go to another site just to play the game.
Even so, it’s a funny little game, one I wouldn’t mind seeing more of in the future, especially if you can find out how to make them either by tricking JavaScript to use a local server for verification, or using some other code base entirely.