When Orcs Attack
The basic gameplay is like other TD games: lay down towers to take out swarms of enemies before they get from point A to point B. Just click an icon to select a tower, click somewhere to build it, then watch the fireworks ensue. The genius of When Orcs Attack is that the interface is simple to start with but offers lots of power to players who want to use it. You can set how towers prioritize targets, cast spells like Teleport which sends enemies back to the start, upgrade and sell towers, and lay down walls in clever patterns. The ability to alter the maze gives When Orcs Attack more tactical depth than most tower defense games out there. When Orcs Attack carries its tongue-in-cheek theme of justification well, complete with a theme song that makes you think of a Fox reality program.
Analysis: Replete with several modes, including crossroads (two armies to contend with), capture the flag, pachinko, as well as the classic maze defense, When Orcs Attack is an homage to the genre itself. It's a nice complement to Immortal Defense, which gave TD games a philosophical slant. When Orcs Attack justifies the genre with a self-consciously simple premise and fleshes it out with a so-generic-it's-sweet aesthetic. All in your browser window, which I'm tempted to say trumps any artistic factors. Tower Defense fans, here is your dulce de leche.
Note: When Orcs Attack requires a plug-in in order to run in-browser, kind of a hassle, but I recommend you make the jump. There's also a download if you want full-screen. The game is open to design adjustments based on the data that John logs from people playing, and improvements will be made into the future.
The download version of the game is a time-limited demo of a full version that goes for $24.95.