Like previous people I must say the boss isn't very fun. The best tactic to beat him (at least on easy mode where you have enough health) is to suicide dash into him to shoot behind his defenses. Although I must say I have no idea how you'd beat him in any way on hardmode seeing as there's so much seemingly unavoidable damage when you run back and forth waiting for an opportunity to shoot him in the back. The rest of the game was really nice. Gameplay ike Ghosts and Goblins but harder lol. And I LOVE the NES inspired graphics.