If you're new to tower defense, the genre is built around wave after wave of different enemy types that come streaming down a path toward a goal you have to stop them from reaching. To do this you build structures in predefined spots around the pathway that spew various sorts of offensive units to counteract the strengths of each kind of enemy. There's a rock-paper-scissors sort of balance going on with characters that specialize in melee, ranged attacks, area-of-effect, and so on. Despite Ninjatown's lighthearted appearance, the potential strategy can get elaborate enough to be satisfying.
In Ninjatown your offensive units are, well, ninjas of various stripes. You've got hand-to-hand and ranged ninjas--with cutesy names like wee ninjas and sniper ninjas--to cover the basics, but then you get into the more unusual and amusing unit types. The business ninja attacks with a frenzied sales pitch, cell phone in hand, distracting and slowing down enemies. Lava ninjas throw fireballs, setting enemies ablaze and doing damage over time. You can sell one ninja hut to recoup some cookies (the game's currency) in order to quickly build a different type of hut. That's a must, because you can only see what kinds of enemies are approaching one or two waves into the future. So it's less about setting up a long-term strategy in each mission and more about quickly adapting your defenses to the kinds of enemies that are rolling in moment to moment.
On top of the many ninja fighters, you've got a few other offensive capabilities. The whole Ninjatown clan battles under the tutelage of the crusty but capable Ol' Master Ninja, who can unleash some devastating special attacks involving the touch screen and stylus when you've earned enough "happiness" from defeating enemies. Actually, the entire game is fully stylus-controllable, which absolutely works in its favor. You employ the stylus like you would a mouse, tapping on ninja huts to pull up menus for upgrading units and setting waypoints and attack preferences. I did prefer scrolling the viewpoint around with the d-pad, but otherwise it's wonderfully efficient and easy to navigate the battlefield and lay down your units using just the stylus.
My only real knock against Ninjatown is, well, it ends. The story mode's 36 missions ought to last you a good while, and you're ranked in each one, so you can always go back and try for better performance in each one. The multi-cart multiplayer mode offers a well-designed head-to-head mode on eight maps where you both face identical streams of enemies, with some interactivity in between. (There's also a three-map version of this available with a single cart.) But the game is the most fun when you're facing off against a previously unseen level, having to scramble to construct the right defenses fast enough to stave off each wave. Since the game is rendered in really simple 2D sprites and tile-based levels (which really fit with Shawnimals' trademark art style), I feel like a random mission generator or, even better, a stylus-based level editor would have provided more longevity. Because I'd like to carry this one around with me from now on, just to battle through the odd new level here and there occasionally.
Don't judge Ninjatown by its cover. It's funny and clever in a way that grown-ups can appreciate, and the increasingly complex strategy is engrossing and challenging enough to keep you coming back right up to the very end.