I felt that there was a certain lack of a hook at the beginning. I had to invest some patience, especially for the controls. For me, a better control setup would be using Move (WASD) with W as jump, and CTRL as the shooting key. CTRL for shooting was good, but the projectile path should be assigned to Space.
Moreover, it wasn't entirely clear to me that I needed to collect all the cards to obtain ammo. They didn't seem to stand out as much as the other elements in the game. Maybe this could be fixed with a larger and smaller animation on the cards or the light behind them, or perhaps with a marker when ammo reaches 0, indicating the need to collect the cards.