Wow. I played as the hero first and got wrecked. And wrecked again and again. But I stuck to the edges of the boss' outline and was relatively safe while sneaking in shots. It felt great to beat him, and as the boss I sort of steamrolled the hero (incredibly elegant solution to implement the boss attacks with a cooldown so they weren't too OP) and thought I would make short work of him, but then when I realized I had to take down all three lives ... what a great surprise. It's one of those moments that makes you lean forward and get into gamer mode.
The 1-bit pixel art is incredible and the sound selection is great, even if the mixing needs some adjustment. It was the perfect length for a jam game and a really enjoyable experience. My only concern would be that the fight as the hero is a little too difficult for somebody jumping in and not ready to repeatedly try to overcome the challenge. Even if the boss speed was reduced slightly, or the attacks had a stronger telegraph, it would feel a little more fair as a player. I beat it, but I almost felt like I was exploiting the game by crouching in the corner and stabbing in at Shadow Link in the Zelda II.
Overall, an incredible solo dev entry and great experience. And I appreciate how much you've been giving back to the community on your Twitter and YouTube. Thanks for sharing.