This is another one of those "reminds me of old school flash games" kind of games. I dig the art style, and, judging by the fact that the map is tile-based, you probably have a map editor of some sort, which would make it very easy to expand and produce new maps.
It took me two deaths to realize how to damage the frog boss, which was probably not very smart of me. I also couldn't find the last hidden gem, if there is one.
Great job!