Perhaps it's because they're easy to design, or because there doesn't seem like a lot of strategy that can be implemented, but the Tower Defence genre hasn't gone too far in recent years. Where every other genre has been making leaps and bounds to redefine itself, TD games seem fairly content with its classic mechanics and simple design. In a way it makes it easy to know what you're getting into. Place a tower down, watch it kill things, rinse and repeat as necessary, it's a simple equation for simple times. That's precisely what makes Defenders of Ardania a nice breath of fresh air, so much about it seems different yet so familiar. It could be one of the few rare branches on a fairly unremarkable tree that yields a noteworthy fruit.
Most TD titles are based around surviving wave after waves of enemy forces, which is largely what Defenders of Ardania supports, but where things immediate take a turn is in what it takes to win a match. Players are required to manage their own troops to send from their own tower in the same way that the computer will be sending units out to kill the player. It's a tower versus tower scenario, where micromanaging the units that move and the units that stay still is fairly vital to victory. It's this extra mechanic that actually adds a layer of depth and strategy to a genre that's largely been a 'wait and see' style of action, whether it be the game's single player campaign or in its multiplayer component.
Players will micromanage these two elements of gameplay using two completely different resources, one based around how many units are on the field while another takes into consideration what towers have been placed and where. Placing a tower down expands the field of control from where another tower can be placed, and since space is being fought over by two players location is just as important as the type of tower that is being dropped. Naturally the playing field is broken down into a grid to keep things fairly simple, and the same rules apply that most other TD games subscribe to. Better towers are more expensive, look cooler, and as players only have a limited amount of towers that can be placed at any one time, they had best be chosen carefully.
Units on the other hand are spawned through a different resource that assigns soldiers a value based on what they do. Faster units have weaker defence while slower ones often times have more health or healing powers. The same way that players must plan towers for a wide variety of enemies, players need to plan sending out units against what could be a series of specialized towers. Ensuring units that can take more punishment are released early, alongside units that quickly optimizes doing the most damage to an opponent's tower. There's a lot to consider, but that may be what makes Defenders such a unique game, depending on how complex these scenarios become (and how many units/towers players will have to work with) gamers could have an extraordinarily deep game at their fingertips.
Juggling between both resources is challenge enough, but the game also takes things one step further by including hero units and multiple tower opponents. Some individual elements like unit control, UI placing, and an annoying narrator for single player mode leave a bit to be desired, but there's still a bit more time for adjustments before its release by the end of the year. Perhaps this is due to some personal taste, but another major factor could be that there's so much being warped from the original genre that Defenders is almost worth being slapped into a general 'strategy game' category just to avoid confusion. Either way, it looks like Paradox has done a fantastic job in redefining an incredible stagnant and ignored portion of the industry.
Keep an eye out for the release of Defenders of Ardania on December 6, and lets hope they have plenty of support planned for the future. Its definitely a tower defence game that's worth keeping tabs on.