Hm. The scoring system is sorta flawed.
For example level 5 is pretty hard and often you die pretty much at the beginning. So, its score-wise benefitical to die in level 4 several times (close to the end of the level), which is sorta silly…
One way to solve that would be using an independent score counter, which’s points get only added to the score if you manage to finish the level. An exception could be made for the last life… this way you would get some more points for getting only a tiny bit further.
(No idea how that time bonus thing works… after all there is no visible timer, which makes the whole thing kinda obscure.)
And something completely different… I actually liked that ultra plain flat shaded look for its retroness