For a first game this is fine! I can imagine that it has been a lot of figuring things out and trying to get your idea into the engine, so congratulations on that :D
Overall the difficulty is a bit low, as you can just keep on spamming the shoot button, so some sort of cooldown would've been a good gameplay addition. I found a little bug, where resetting the game after dying does not reset the high score to 0, so it's always incrementing :P