Uhhhh, I think I have a problem.. I don't know how you did the music for the game, but I played your game to the point where it stopped playing the music for me HAHAHAHAHA! I'm pretty sure I've played for more than an hour, and like at one point the music just stops, so... I guess you didn't account for this happening haha. It was just that fun! I was planning to try and get all the upgrades maxed, but then at a point I was just wondering if some of them didn't have limits to how many times you can upgrade them (bullet damage, bullet penetration, increase crit damage or chance idr which one, and increase hp all exceeded the twos digits for me haha). The game loop is simple, but I think a combination of both the general gameplay and the small details to add feedback is what kept me playing for the long run! Everything from the bullet sound effects, the damage indicators that pop up every hit, to just the natural progression system made blasting enemies so much fun! I got to give props especially to the bullet shooting sound effect, when you have like max reload speed, it just sounds sooooooo good, so nice job! I like the art too. Its simple and not distracting, which makes it easier to tell whats going on when there are so many enemies on screen. For suggestions, I think bullet fragments are a bit too overpowered. Once I bought the bullet fragments, I went from dying at around wave 12 to having to kill myself at like wave 26, because I wanted to spend my upgrade tokens. I think instead of bullet fragments spreading after a bullet comes in contact with a enemy, maybe it would be a bit more balanced if it spreads after an enemy dies (bullet fragments made bosses too easy, but thats just a personal opinion).
Overall, this was a really addicting game! Although it wasn't the most creative game, it sure was handled and developed really well! The levels were all paced nicely in the beginning, smoothly giving players more power as they play! The only way to go from here are environmental interactables and other enemy variants, which would be very interesting to explore if you were to continue developing this game! Other than that, I really had fun this one! Great job!