To make a control and arrow key type "Arrow(Direction)". Such as, "ArrowUp" for the up arrow and for letter keys it is just "a" or "z". (Do not put quotation marks.) You also have to click on the game before you can play it. You'll have to fullscreen and maybe zoom out to play properly.
Player 1 Left:
Player 1 Right:
Player 1 Up:
Player 1 Down:
Player 1 Attack:
Player 2 Left:
Player 2 Right:
Player 2 Up:
Player 2 Down:
Player 2 Attack: