BigFraudBigFraud here, coming from One Shot, One Kill.
This was really cool! Took me 2 tries to beat the boss and it was quite satisfying. The music choice and sound effects were great! I kinda wish the movement speed was a little faster, but that's just a personal preference. The game is quite fair and doesn't feel like BS. I especially liked how it got more difficult as the boss' health got lower
One little thing I noticed is that if you shoot too fast after shielding your shield will block your own shot. I'm not really a stickler, but each one of those were shots I coulda had on the boss lol. You could set your shots to ignore certain tags so that they don't collide with the shields collider or disable the collider faster if you used Mecanim. That's just my two cents though!
Great game!