I had a great experience playing this game. It held me until I found the boss and it killed me. I loved the reload mechanic (especially using the rifle) because it allows you to plan your actions and pick the right weapon, and the variety of guns contributes a lot to the gameplay. The movement feels weird due to the lack of diagonals and some collisions detection. I think more heal tanks are a need, and also a couple of illustrations in the intro.
Finally, I loved the visual style, sound effects, and music. Overall, the game feels juicy and well balanced. Great job!