Tower Defense is, essentially, simplified real-time strategy. Waves of enemies come at you and you must juggle your resources to build towers in places you deem appropriate in order to protect your base. All of that is true of Trenched, the latest game from Tim Schafer's Double Fine studios (the Psychonauts team) and Microsoft Game Studios. To keep things interesting, you control proceedings from a huge, mobile trench. Hence the name. Clever, eh?
Your trench isn't just for running about and looking at the battlefield though, oh no. Instead, it's from here that you deploy turrets (gotta get close in your trench to do so) and even dispatch the evil enemies with guns installed on the thing - all of which is customizable, right down to the paint job.
Gameplay is presented from a third person perspective - far enough out to give you a reasonable idea as to what is currently of utmost importance for you to focus on, close enough to see the glorious artistic flourishes that everything in the game is embellished with. It might be a download-only game and it might be lacking in terms of high-res textures, and rendering technology, etc, but like true artists, the team at Double Fine have managed to achieve genuine flair and personality with their limited palette. Characters, enemies, and even environments all have their own, unabashed, and unique visage that really brings them to life.
The story is a cool, alternate World War II affair, in which survivors of a mysterious and deadly radio wave find themselves suddenly incredibly able-of-mind, despite being disabled in body. One of the pair uses his new powers for good (inventing the trench / mechanical legs for disabled veterans) while the other... he goes a bit loopy. A new war, then, is formed - you and yours versus the evil mastermind and his "tube"-based minions. It's exciting, retro-themed stuff and creates a narrative compelling enough to provide more than just context for the gameplay itself.
In addition to upgradeable turrets, as is the norm for the TD genre, there are also loot boxes to collect, which can contain "random" items (it's not clear if they're random or not, but they seem randomish) with which you can upgrade your trench. Items can also be purchased from a vendor, however you generally find the best items out in the field. They use World of Warcraft-like colour coding, with the particularly good / rare item drops conjuring up that indescribably compelling desire to keep playing just for a chance at a shinier gun.
The difficulty seems set about right, with levels challenging you to think a bit without frustrating you by requiring that you adhere to exactly the designer's layout or placement sequence if you want any chance of success. As you progress, the required strategic thought and twitch finesse ramps up, of course, but it does so at a reasonable pace without spiking as quickly as you might have experienced in a hardcore TD game.
Whether the gameplay is for you or not is something that's quite hard to predict. Tower Defense purists will likely feel encumbered by the close-in camera (compared to the more usual top-down affair) and the need to run around to place turrets etc, while action people might wonder what all this turret nonsense is about. If you're in either camp, looking for a bit of that green grass over the fence, Trenched manages to leverage the best bits of both worlds well, adding action into Tower Defense about as well as it adds strategy into Action.
As for me? I consider myself something of a TD nut (I have literally dozens of the things, on pretty much every single one of the many gaming-capable systems I own) and I love it. It doesn't replace TD for me but it provides a nice variant on the same experience, down in the trenches as it were.
It's not perfect but, instead of the faults (little things like visual glitches, etc) piling up to become an unbearable thorn in your side, they're more like the eccentricities of a favorite uncle. It's whacky, weird, and wonderful. If you're at all interested in Tower Defense, you absolutely must give this one a go.