Game is very simple with straightforward goal and perfectly fits the theme, but still has very unfair obstacle - the fireballs. Some are easily avoidable, but because their speed is random, some are flying too fast and you can't possibly react, thus it doesn't feel great to be killed in it - as it doesn't feel like a player's fault much. The shield allows to mitigate the issue, so the gameplay loop is from shield to shield, which makes the game intense, but still, the randomness is imho killing the fun. Introducing the shield makes me think, you might have the same issues when developing the game, isn't it? :D The music is also not very fitting the game, it rather distracts and make me want to turn off the speakers sadly :(
Other than that, it could be really enjoyable, simple collecting game base.