Very stylistic game, nice work.
The good:
- The black shadow along each pixel sprite gives the game a cool elevated style, and the colour palette presets all give nice options for customisation.
- The gameplay feels super smooth, the screen-shake when firing the gun gives the game a nice weight. Controls are very responsive.
- The sounds and music all fit the games graphics perfectly. The particle effects make the game feel polished.
Improvement suggestions (this is my opinion, not saying you have to do this, just suggestions):
- I was clicking rapidly until I found out holding down left mouse button lets you fire infinitely, so most of the time I was just holding this down. This seems a bit pointless, since in what situation am I not going to want to shoot, right? Perhaps the player could automatically fire, or maybe there is a cooldown, so if you are firing for to long, the gun needs to cool off. This way, you need to be more strategic about when you are firing. Or, maybe just one click does one shot but that's not as fun as the previous idea.
- The ship movement was a bit disorientating at first. I was expecting the ship to move relative to the direction it is facing. This is more of a minor point, since it doesn't take long to get used to the controls, but still thought it was worth mentioning.
- There isn't much of a reward system in place. Sure, I want to beat my previous score, but that's just a number. If I unlocked something each time I played, or was given a progress bar showing my next unlock that would be cool. In fact, you could already offer the colour palettes as unlocks, since these are a super-nice feature already included in the current game.
Overall, super nice work man, you already have a great game here. Looking forward to seeing what comes next. :)