Hey, I liked the game overall, but had to stop playing after reaching the first boss because of the screen shake. It was a bit too frequent and I get motion sickness very easily. I would love to give it another try if you can make it optional. It is usually one of the easiest things to make optional, so I hope you can figure that out. Otherwise, I liked almost everything.
It was neat to see RPG-style levels and stats. I think that can add a lot to the gameplay, especially if you want the game to be long. I liked how you replenish your health when finding an upgrade or leveling up. I happened to need some healing both times when those things happened to me & it felt really nice.
I liked the ability to destroy or deflect the projectiles. I had trouble with the zombies at first but they were manageable when I realized you could do that. It was also neat during the boss fight to use its own attack against it.
The graphics were nice! I liked the character sprites significantly more than ATS's (you did both, right?) I didn't get to hear much music & the first area had pretty subtle music, so I will withhold judgment on that & hopefully get to hear some more later. It's also nice to see a full story & cool cut scenes.
The only thing I noticed that would be good to change (other than non-optional screen shake) is the loss of progress when dying. It would be good to let the player keep as much of their progress as possible, such as permanent upgrades, map progress, and defeated bosses. It just feels really bad & it's not really necessary since you already get punished by getting knocked back to the checkpoint. If you want a harsher penalty, I would suggest taking away something like money or experience. A lot of games do fine without having a harsh penalty for death though.
Besides making the player feel bad, it's even worse in metroidvanias than other games for a few reasons. You can easily lose track of which areas you've explored since it's non-linear. You have to spend time repeating the same areas and challenges, while one of the key elements of metroidvanias is exploration. It can also discourage exploration and other kinds of risk-taking if the player is too scared to die and lose progress. They might feel the need to walk back to the nearest save point instead of moving forward despite it not being fun. They also might skip things that seem optional to avoid the risk of dying before they can save.
Really good stuff overall & if you make the screen shake optional, I will definitely play the whole game later on!