Every once in a while, you play a game that, while not revolutionary, seems to successfully combine everything great about games of its genre. When you come across a game like this, the whole of the game seems to fit together better than the sum of its parts. That's how I would describe Kingdom Rush, the shining jewel in the crown of the fairly recent genre of "tower defense" games.
Kingdom Rush isn't just your standard every day tower defense game. I would hope that much would be obvious just by what was stated above. In fact, there's few tower defense games that I would really compare to it, although that may largely be due to my usual avoidance of the genre. On first glance, it's easy to notice that the game seems to take some heavy influence from the Warcraft games. And no, I'm not talking about World of Warcraft, but the real time strategy games that came before it. Of course, Kingdom Rush can't really be classified as such, because, well, it if was a RTS, it wouldn't be a TD!
Naturally, the influence from the old Warcraft games isn't quite as much in the gameplay as in the artwork. The cartoony style and colors of the graphics do evoke the look and feel of those games, but also adds its own distinct character. But, enough about the graphics. How does the game play?
I'd have to say it plays pretty damn good. You start each map in the overarching story of the game with money, and possibly a few starter towers. You can then proceed to build towers of soldiers, archers, magicians, and artillery. Each tower you build can be upgraded as you go through a level and collect money from slain enemies. The tower upgrades aren't completely linear, either. Once you have progressed through the game, your towers will give you different branches of abilities, thus allowing a good variety of different towers to guard against the rampaging hordes. It also gives you quite a bit of flexibility in how you want to stage your defense of a level.
Your upgrades don't end with just your towers. Once levels are completed, you can earn stars, the amount of which depending on how thoroughly you were able to complete the level. With these stars, you can purchase upgrades for pretty much everything in the game, ranging from your towers' abilities to the strength of your reinforcement troops. The game gives a great amount of replay value once you have completed the first time around, allowing you to go through and beat various difficulty levels of each map as well as giving you a few more to complete.
If there is one gripe I have about the game, it would be about its insane difficulty. There are one or two levels that can be difficult to complete even after beating the game the first time around and earning some decent upgrades. Also, the difficulty of the bonus levels that open up later is completely retardedly insane, and pretty much impossible to beat.