I really love this! Gives an old Sega Genesis kind of vibe. Really fun, lovely atmosphere, gorgeous art. Simple yet engaging. A really nice blend of genuine scientific inspiration and cute, fun gaming!
The only feedback I would give (same as someone else below) is restarting just the level you're currently on rather than going back to the beginning when you lose would be nice, as it's a little demotivating returning to the beginning, especially with such a cosy atmosphere game. This relatively easy to implement feature would be enough, I think, to make the game sellable! :)
(If you wanted to go a little more complex, you could return to a puzzle selection screen after losing, allowing you to chose any of the levels you've already played, while having future levels locked. This would also give an idea of progress, i.e. how many levels remain).
Really nice work!!