It's quite fun! Good job! Love the visuals.
Some feedback:
I found the game a bit confusing to understand at first. It's not hard to pick up and play, but could use a bit more of explaining things. For example, I had a hard time understanding the corruption mechanic, especially because the tutorial states that you get damage the more you stay in it, so I figured I'd avoid touching enemies only to later figure out there's really nothing at all it's just a stage thing that keeps damaging you.
It really needs some sort of visual cue for enemies that hurt you. In stage 1 nothing could hurt you, in stage 2 however, not only it was a suprise when the green enemies attacked, but also when it spawned out of nowhere some new enemies that are super fast and kind of difficult to see at first.
A targeting mechanic should be looked into, or a priority system for the auto-targeting. Countless times I wanted to attack a green enemy only for the game to target something else instead.
I found a bit jarring at first how the ship moves towards the mouse, not to mention I sometimes wanted to just change where I was aiming at and ended up moving towards danger. A toggle for the movement or a button to stand still should really be looked into.
Progression is quick and fun, but lacks strategy and often times, the upgrades are a bit too cheap. There's really not a lot of room for skill, it's all somewhat dependent on the things you unlock. You can't really beat the boss without life/shield upgrades and the boss damage perk, for example. Positioning doesn't matter all that much.
It could use some more feedback for when getting damaged. Think knockback, or changing the ship's color.
Movement is not that important apart from dodging some enemies, maybe consider implementing mechanics to make it more of a core feature? I'd also recommend changing or giving the option to change the ship's control to WASD, especially if you're planning to add things such as enemy projectiles.
The progression in general could be tweaked slightly, especially things such as spawn rates. It's very quick to get a lot of enemies on screen, unless if the full game is meant to be a couple more extra stages, this will get out of hand very quickly.
The "code" text in buttons while cool, make them a bit difficult to understand. I suggest having an option to turn it off or just not doing things that way.
Consider having a way to heal the ship during the run or reduce corruption damage over time (perhaps the less enemies that are on screen, the less damage over time you get done to you). Either a power-up or simply just the green pick-ups, for example. It's very demotivating when you get damaged and know you won't have enough HP left to fight the boss and is going to have to start all over again. Which, again, is not a matter of skill, but of how much HP you have left and how much corruption damage you get over time.
Bosses should offer some unique challenges other than just being damage sponges. They should be the thing you're upgrading towards, sure, but they need to be a bit more interesting. Consider giving them collision, having them throw projectiles you have to dodge, maybe giving it a shield that gets deactivated for a short amount of time after you kill X enemies, anyways, I'm just spitballing, I'm sure you'll find some cool ideas to implement.