Nice game !
When the Bonus Draw is reached, the opponents face each other and the music ends. After a while you will hear a beep. If you fire your weapon before the beep, you automatically die because the opponent shoots (because you didn't follow the rule either). If you are the fastest after the beep, the opponent falls and you advance to the next level.
But unfortunately you are slow. :)
When the beep sounds, you have 0.5 seconds to shoot. Try testing here: https://www.justpark.com/creative/reaction-time-test/ :)