Five awesome iPhone tower defense games

Protect your shack from the undead in the amusing, innovative TD game Zombie Attack.

If there's a bigger game genre for the iPhone than Tower Defense clones, I haven't found it. A quick search of the App Store reveals well over 100 titles matching that description.

No surprise there: the iPhone's touch screen lends itself perfectly to this kind of game (which, for the uninitiated, requires strategic placement of defensive armaments to ward off increasingly powerful attackers).

OK, but which TD titles are worth your time--and cash? Here's a roundup of my five favorites. It's by no means a definitive list, but I think fans of the genre will enjoy them all.

• Bloons Tower Defense Balloons. Monkeys. Darts. Nearly everything from the beloved Web-based classic appears in the iPhone version. The controls are a little finicky, but if you want to introduce young kids to the world of tower defense, this $2.99 game is the one to get.
• Navy Patrol: Coastal Defense Though the learning curve is a bit steep and the onscreen action can get a little cluttered, this naval-themed, open-path TD exercise offers some of the most in-depth and challenging gameplay I've found. And the $1.99 purchase price includes new maps as they get added to the game.
• Ninja TD Like Saturday morning anime come to life, newcomer Ninja TD delivers dazzlingly colorful action and animation, all centered around a martial-arts theme. It's currently on sale for 99 cents.
• TapDefense Tower defense freebies are few and far between in the App Store, and good ones are rarer still. TapDefense may be a year old, but it's still a great introduction to the genre and an enjoyable challenge.
• Zombie Attack Just in time for Halloween and perfect for zombie fans (you know who you are--braaaaaaains), Zombie Attack ($2.99) offers amusingly gory and innovative TD fun. No mere tapping-for-turrets here: you run your character around the screen by tilting your iPhone, then set up turrets where needed to stop the open-path attacks. Seriously fun. (Watch for the prettier, bloodier sequel, Second Wave, which is due this month.)

Wow. Ninja TD's got it going ON in the graphics department.

What, no FieldRunners? That's arguably the best, and most popular, TD game in the App Store, and it's been around forever, so I decided to focus on some lesser-known titles.

Now it's your turn. Hit the comments and nominate your favorite tower defense game(s).

By the way, proof positive that great minds think alike: Download.com's Jason Parker recently posted his own list of tower defense favorites. Check it out and see if you like his picks better than mine (keeping in mind my fragile ego).