Certainly, a good game! I actually thought, it was a real GB game! Well done!

PS: Feel free to try my game out! Cheers!

There's a cool concept here, for sure! I think you need some secondary form of movement, simply cruising along through long hallways feels a bit un-engaging. Adding a dash or a brake/drift to break up the monotony would help a lot, just something to make movement less robotic (or drone-ic, I guess). It could be a Metroidy powerup, and allow you to bypass some kind of obstacle.
I'd also beef up your bullet sizes to make shot collisions more reliable. I think everything has a little too much health right now. Maybe that changes with weapon powerups, but there aren't any quickly defeated enemies, and bosses are currently big 'ol health sponges.
I'd love to see where you go with this!