The text was saying "Press enter to play" but I had to press space.
Then, I didn't realize I was controlling the boss, and I was spamming attacks on it :D
After I realized what was going on, I played this like 4 times in hopes of defeating "the hero". Got up to the green form (the one after the black one, if there's an order -- or like 6 heroes in if there isn't).
Every aspect of the game is really polished, but it was kind of a bummer there wasn't much gameplay with the hero.
Good entry, overall!