Some games don't really set out to break a genre in half. Sometimes, people just want more of the same. Age of Thrones [Free] is one such example, as it doesn't really change the tower defense formula in any way, but should offer up enough fun for those who can't get enough.
No, this "thrones" has nothing to do with Hodor, Bran or Daenerys -- but there are dragons! Age of Thrones pits you in a familiar spot, locking you in mortal combat with the Dark Lord of the Thrones to save the land. It's a familiar and generic story, yes, but there is a good amount of humor built into the narrative to give it a bit of character. There are a number of references to films like 300 to help ease the experience, and the vibrant graphics help brighten up the mood even more. Said visuals don't tend to take advantage of the iPad's power as much as they should, so the game is perfectly fine on a smaller device.
Thrones is yet another tower defense game that's "maze-centric" in that you'll focus more on positioning your towers to shift creatures into the longest path possible. Maze-likes tend to be more strategic in nature as you have to plan out a rather intricate string of towers, complete with period slows, AOEs and other types, but that also means it can get pretty tedious doing the same concept over and over. Thrones tends to mix up the enemy variations a bit, throwing in flying creatures to help keep you on your toes, but it can get really frustrating to spend 10-15 minutes building a complex contraption only to find it fall flat on its face a short while later.
There are 16 towers to help break up the monotony, but you'll have to play through the game to unlock them. In addition to placing towers you'll have the opportunity to cast spells via the touch screen, which helps add to the interaction level when you're just sitting there watching your maze do its work.
If you're a tower defense junkie there's plenty of content on offer here, with tons of levels, difficulty modes (including one that disables the selling of towers and pausing the game), and upgrades to unlock. I especially like the unique choice to play the game on normal and risk earning a zero to three star rating depending on your health, or gun for Hard and earn a flat three stars.
Should you find yourself groaning at the mere mention of "towers" on a mobile platform, Age of Thrones is not for you. In fact, if you even feel a minor wince coming on, it's probably not for you either. But so long as you can stomach creating mazes for hours at a time to fend off droves of demons and dragons, you'll have a good time.