Hello! There's a tutorial written at the beginning of the game teaching how to drag ammo into the gun manually, maybe you skipped it. Here's a video @seyeroteb made finishing the game.
Hey! i decided to place the cards to increase the replay factor of the game, the game remains simple and you still only need 1 button to play. I want to add more cards and improve the visual feedback for them in the future. Thanks for your comment and feedback! \o/