Thanks for giving it a go!
Originally I was thinking to make a mix of a classic scrolling shooter (Life Force -esque, so such Gradius) with a classic beat 'em up (Double Dragon -ish) with a robot transforming between them, but in the end of the day I had too much fun designing the shooter.
The second boss is the most difficult part, and with so many people struggling I wish to make the easy mode a bit easier to discover (you can only see it if you lose at least two times on the same level). That is a very good lesson for me to learn!