Wow.
Never have I known how much a single video game sample could drive me to manslaughter. I am glad that in this case it is merely dogslaughter. This is a fine first stab, although in need of refinement. If you could obtain the original sprites and background, you could be well on the way to something great. The sample, as annoying as it is, could be used more sparingly in conjunction with other sfx from the game, an authentic NES blaster sound would not go unnoticed in a game such as this, baring that, realistic gun sounds. Mix it up, add some variety to the punch and you've got yourself a party.
Keep grinding.