Click the red/green samurai to kill them. Once you kill 20 of them, the Boss Battle will start. Click the grey samurai to attack him. Keep doing it until he dies. Your health and the boss's health is shown in the top left corner. When you're in the outro, hover over the two projects on the sides. Then double click the links on the side lists and press Ctrl+C or Cmd+C to copy the link. Then paste it in your browser.
The art for the samurai sprites are from @dac2025be The art and some of the coding for the katana sprite is from @40Cooly The coding and some of the art for the outro sprite is from @ImRohan10187 The backdrops are from Google Everything else by me.