the programming and artistic skill is there but that's not the main component of a good game; that's the hard part of game design to make an appealing game. The level lacked direction and the enemy units were placed randomly and sporadically with no thought. The health system was catering to a style of button-bashing brawling-- which I didn't even bother with since the gameplay got monotonous after the first 4 kills (3-4 unit types with nearly all the same kind of attack, and that constitutes hundreds of instances of units). The movement mechanics got boring and stale since there's nothing special I'm doing with it. If you're going to go with a ninja theme, your game should embrace the ideas that make a ninja a ninja: fast, stealthy, deadly, etc.
More thought needs to be put into game design, regardless of technical skills in flash.