This is such a good fun premise and the gameplay mechanics are simple yet fun! One critique that I think would improve this game would be to have the opponent just punch more. Oftentimes, I would find myself just trying to follow my opponent, begging for him to hit me. But if opponents punched more often and were not always straightforward, I think it could be more fun basically trying to run into the opponent's wild misses.
Overall, the game is super fun and I would encourage you to continue developing this idea!