From the screenshots, I was not expecting to jump right into a bumping soundtrack with a full opening cutscene. What a treat! Maybe I'm the odd one, but I think I would have preferred WASD for movement and shooting and jumping with my right hand. Either way, the gameplay was addicting enough, quick enough and just the right level of challenge that I jumped back into each new round ready to tackle the boss with my new knowledge of his attack patterns. It took me until my second run to realize I could just hold down shoot! My hand was killing me before that.
I had to beat it twice. The end screen was confusing for me, I thought I'd died and not succeeded the first time because I was down to my last bit of health. But when I beat it again with more health I realized that was the ending.
This was a fun, quick romp. I'd have turned up the sfx on the gun a bit and maybe added a noise when you take damage, but overall I really enjoyed my playthrough.