Wow thanks a ton for the feedback!
The new spell indicators is something I was mixed about too. Putrid S4nd's restrictions with pico 8 is what resulted in the really elegant design of showing the spells on your ammo counter. For this game, I wonder if I could double-up and show both the spells on the left and show a mark on the ammo counter. I could also experiment with having them on the same side of the screen, or even just make this all into some kind of game option (like an option to show spells on ammo counter or something). Either way, this is exactly the kind of feedback I was looking for, I'm sure in the heat of battle it's tough to keep switching between both sides of the screen.
I like your idea of removing the platforms in the early levels. Like you said, it'd incentivize players to practice shooting up and also practice dodging enemies.
Ah yeah the weapon mods text was something I was being strategically lazy about, but I got the same feedback from others during initial playtests. I was originally keeping it minimal with the hope that players would, over multiple runs, learn the mods based on minimal text / icons. But like you said, it feels pretty bad to pick a mod only to realize it does something you don't want it to do. I'll look into adding some contextual text that appears when you move under the mod so players know what they're getting into.
Boss battles are usually my favorite part of development, so I'm glad you liked them! The shockwaves for the zone1 boss's slam were the most common thing to hit everyone who playtested initially too, so I definitely need to make them a bit more visually prominent.
Glad you enjoyed the game! I'm really excited to continue working on this and release it, though it might take some time. Thanks a ton for the feedback, this is exactly the type of stuff I was looking for.