The main mechanics and the game itself were fun. I liked the special attacks, and thought they were cool. The history was good enough for such a short game and enough to give it context.
However the game has some serious flaws. First of all, the enemies were uninteresting and repetitive, as well as the bosses. Most of the enemies were the same throughout the game with just a different color palette and a different attack pattern. The bosses just had two attack patterns so they were easy to memorize and their fights became boring.
The main problem I had was the lag. It became very annoying since the fourth stage, and in the fifth one the game became unplayable. It happened when a lot of things were on screen. I found it very unfair to die must of the time just because of that.