There are three reasons as to why I called it 1291. The first reason, as you already figured out, is because the inspiration is comic 1291. The second is there was a demo game that came with Game Maker 6 (the first "engine" I ever started messing with making games on) called 1945 that was a side-scrolling shooter. The third is that the only other option I could think of in the time was just calling it "Shoot the Moon", which honestly might be a better title as it does what it says on the tin.
Just getting vertical movement to work nicely together was a big hassle for me. As I have mention several times before, this entry was made in 5 hours, and it had been over a year since I had last used Unity. To add horizontal movement to the mix as well would have taken more time than I had, but it will probably be added. That said, I have been idly thinking of other was to do the horizontal movement, without actually moving the character. Mainly, slowing and speeding projectile's horizontal speed by pressing back or forward.
The shooting might feel less tedious if there were more things to shoot, but thank you for the feedback. I might not change the speeds as they are at the moment, but instead introduce difficulty settings and part of the increased difficulties is an increased speed modifier.
You're quite right. At the moment, it is a very boring game. I knew I didn't have the time on my hands to create an full game or even the full boss. Maybe if I had the full weekend, maybe. So my goal was to make it as mechanically complete as I could in the time I had. As such, you can move, shoot, damage things you shoot, kill the moon, get hit, get killed. At a very basic, fundamental level that is everything you can do in the game. All the variations on how you do it is additional content rather than additional features.
And good to know about the art assets. That said, I would like to either make, or talk to some art-y friends about making, assets specifically for the game. As is apparent up-scaling snippets from the comic does make a high quality sprite.