If you like tower defense titles, the free Dragon Hunter II is worth checking out. You're a lone soldier defending your castle from an onslaught of air- and sea-dragons. You start out with a simple bow and arrow, but later you'll have the chance to obtain more-advanced weapons.

Game-play is pretty simple: To aim the arrow, you just point at your target. The arrow's power, on the other hand, depends on how you drag your finger across the screen, with the amount of drag determining the power. It's a little confusing to explain, and it takes some getting used to in the game, but after a few levels you'll be a pro.

Completing a level earns you gold, which you can spend on upgrades and food. You'll need food to keep your people alive; but if you manage to survive in later levels, a boat will automatically deploy from your fort and someone will collect dragon meat for you. So with each level you use up food, but you'll also gain food (assuming that your meat collector doesn't get killed).

Upgrades include better weapons, more arrows, and a stronger fort. But these improvements are pretty expensive, and you don't earn a lot of gold in the first several levels--so the game action can take a while to pick up.

All in all, Dragon Hunter II is a decent tower defense game that eventually gets quite challenging and interesting--but "eventually" is the key word here.