Thank you for your detailed comment! I'm really glad that you find the challenge to be just right, my games tend to be too hard for many people so this time I wanted to make sure and balance the game so that jam participants would be able to clear. So far everyone I see was able to beat the boss and didn't complain about the game being too easy, so I see this as a success!
Regarding the things you pointed out - due to the jam version's length and how intense the stage 1 track is, there wasn't really much room to fit even a small tutorial on player abilities. So instead I tried to keep their mechanics simple and intuitive as soon as you try them for the first time - when you use the bomb/hyper, the sequence of events that always happens is: bullets turn into items > items get sucked up after a short time > hyper gauge or score increases on each item collected. In-between each event there is a short amount of time during which the player can "register" what exactly is happening - about 0.5s per event, so pretty short time, but each event individually is pretty simple and there are no complex conditions or mechanics, so should be possible for the player to learn each effect on their own.
Hyper is slightly more complicated because it adds two more events (... > player shot gets empowered > score items start to come out on each hit), they both happen within the same time window without any delays or time to mentally register, so it makes total sense why you'd want more information or relaxed opportunity to learn how it works. I'm really not sure what I can do to help with it that would fit with the flow of the gameplay but I'll keep it in mind, maybe there's a simple solution to this problem somewhere
Thank you for reporting about the resolution - in all my time using this engine I've actually never tried Windowed mode which is admittedly a pretty huge oversight, I've relayed your feedback to the engine developer so the way it works might change in the future to something that makes more sense. Thank you for playing, I'm glad to hear you enjoyed the game so much!