Select your fighting skills in a deck of cards that you assign. Go into battle with different monsters and defeat them wave after wave. Use the directional keys to move your ninja around the board on your side to dodge attacks and also get in line with the fighters on the other side so that you can attack them. When the monsters is on the line move up to line and then you will be able to land some melee attacks on them instead of just tossing shurikens. At the end of each battle of waves check your skill cards and see if you can do anything new. Also check to see if you can buy more powerful weapons.