Pretty simple but that's a good base to develop.

You shouldn't lock the shoot rate to make it looks more like a clicker game.

I had absolutely no idea that scratch could export to html like this! A very literal interpretation of the theme that fits nicely. In terms of game design,, I probably would have the darkness enemies only do one damage to the player than disappear. You could then give the player just a handful of lives and then avoid the messy business that happens currently when they attack. Given some more time, this could become an interesting take on a tower defense or clicker game!