This is a strategic assassination game, sneak by all the guards and elliminate "only" your targets. You are provided with limited means to disposing of the guards but you will not recieve the points bonous and your ninja rating at the end of the game will be lower. In other words it is a game of selective difficulty. You become faster with every level and you also recieve addtional abilities such as moving while stealthed and snunning fist, which allows you to stun certain guards. keep out of sight ;)