Wow, I had a blast playing this.
2nd boss was the trickiest (I found an 'exploit' you can damage the boss himself instead of the turret in the first phase, which sort of broke the final phase, but then decided to let him kill me so I could beat him honestly). The first and third bosses were difficult but manageable and I absolutely loved the quips. Sometimes the dash didn't go in the direction I was trying to dodge in.
The pixel art graphics were simple but very imaginative, especially liked the casino hall and all the creative alien designs. Also you definitely get plus points for the awesome storyboards at the begging and end!
On the technical side I wasn't able to play this on my widescreen (2560x1080) monitor and had to use my 4k one instead (that worked perfectly).
Great effort!