Mario Gunman:

Evil Bowser attacked Mario’s bank and captured all the gold coins in absence of Mario. Now he is attacking Mario’s castle to capture princess Peach. Only Luigi is present in the castle to defend and save the princess from Bowser. Your objective is to help Luigi to defend the castle and destroy as many enemies as possible with your gun. Use your mouse to aim and left click to fire, use A and S keys to switch between weapons, and number keys 1 to 5 to select various weapons. You will earn coins by killing enemies and you can spend that money to buy newer weapons and upgrades from the gun shop in between the levels.