Plants vs. Locusts

by Peter Eykemans

Genre-blending
isn't a new concept. You've probably heard of dramedy films, you've
seen RPG elements in, well, everything, and hopefully we can all just
forget about rap-rock. But there's a unique sub-genre of gaming that's
crept its way deeper into mainstream shooters. It's a way to think
tactically and test the limits of how many enemies are too many. I'm
talking about Tower Defense and how it's landed in Gears of War 3 and Call of Duty: Modern Warfare 3 this fall.


There are plenty of games that have incorporated different elements of
Tower Defense, but Gears of War 3 and Modern Warfare 3 are the first AAA
shooters to blend them all into Horde 2.0 and Spec Ops, respectively.
But what makes a Tower Defense game? Let's break it down.



Currency






Money makes the world go round. Tower Defense needs money to work,
though the element isn't exclusive to the sub-genre. Most games require
some kind of currency to operate, but for Tower Defense it's the
baseline that builds your strategic defenses.


In traditional Tower Defense games, players earn currency from defeating
enemies on the battlefield. Like the earnings of a large-scale hitman,
every death pays out in virtual dividends. In Desktop Tower Defense and GemCraft,
you'll gain small amounts of cash for every kill. Alternatively, in
Plant vs. Zombies you'll nab coins for kills and sunlight for patience
to fortify your botanical army. In hybrid RTS-Tower Defense games like
Revenge of the Titans, you'll mine in addition to earning cash for every
kill. This is an element that can be infinitely detailed, but here's
what the two big shooters have taken away from it.


Every single kill in Gears of War 3's Horde 2.0 adds cash to your total
that can be spent on fortifications, upgrades, and more. Tackling bonus
objectives throughout the map will also provide additional cash. Modern
Warfare 3's Spec Ops takes this same approach, though spending your
spoils varies in both games -- but we'll touch on that in a minute. It's
a simple concept, I know, but a standard of Tower Defense.


Wave Survival






Wave Survival is the most prevalent element pulled into other genres
from the basics of Tower Defense (though one can argue Survival is at
the core of all games). Historically, TimeSplitters
was one of the first shooters to implement surviving wave after wave of
enemies in its Last Stand mode. MechAssault touched on the form with
Grinder a few years later. Both a test of stamina and patience, Wave
Survival's a simple idea that continues throwing challenges at a player
until they collapse, toss their controller in frustration, or (most
likely) both.


Lots of games use a similar mechanic, but 2008's Gears of War 2 gave the
world Horde mode which gained immediate popularity. Halo: ODST followed
up the trend with Firefight, which is also found in Halo: Reach. After
these two huge games stepped onto the mainstream scene, survival modes
showed up all over the place. Left 4 Dead, Call of Duty's Zombie Mode,
and Earth Defense Force: Insect Armageddon all show off their own
versions of Wave Survival, to name a few.


Gears of War 3 expands the idea of Wave Survival by offering Horde 2.0 and
Beast Mode, a reversed version of the original Horde mode. In Beast
Mode, Locust beasts battle increasingly difficult waves of COG soldiers,
beating them down and unlocking more powerful monsters to control along
the way.


Spec Ops as a Survival mode in Modern Warfare 3 is a new concept to the
series. Modern Warfare 2 first introduced Spec Ops, but the original
version was only filled with cooperative challenges for two players.
Modern Warfare 3 retains the player count, but now pits players against
endless waves of soldiers, suicide bombers, attack dogs, and more.


Fortifications






Fewer games utilize Fortifications, compared to the other two tenets.
Placing Fortifications is where creativity, strategy, and luck, come
into play.


In Tower Defense games, players drop towers, turrets and blockades along
a set path where enemies swarm. The shooters with Wave Survival we've
discussed so far don't include the strategic placement of such
structures. While Zombie mode from World of War and Black Ops has
barricades to hold back the tides of the undead, they're locked to
specific entryways. Turrets aren't a new addition to shooters either, as
everything from Team Fortress 2 to Brink allows players to drop these
offensive emplacements on a whim at any point on a map. Due to the
shifting nature of gameplay, these examples don't fit the mold we're
examining.


Gears 3's Horde 2.0 provides five options for building Fortifications.
You can barricade throughways, place decoys of varying believability and
strength, drop sentry guns, build turrets, and spawn Silverback mechs.
Depending on your cash flow, you can repair and upgrade any of these
elements to help the fight. Certain Fortifications are locked to certain
areas on each map, but compounded by Wave Survival and Currency, Horde
2.0 is a Tower Defense shooter mode.


Call of Duty: Modern Warfare 3 does something similar, but goes big in
the elements that one can purchase. Once you fill your wallet with
money, you can purchase new weapons, turrets, and explosives. For a
little more money, you can call in a helicopter to deliver AI troops to
help turn the tides. And for the rich, you can call in an airstrike to
cleanse the playing field of unwanted baddies. Like Gears of War 3,
Modern Warfare 3's Spec Ops Mode incorporates the trifecta.


Shooters like Monday Night Combat and Sanctum
fall into the Tower Defense shooter category, but feature the gameplay
exclusively. Trenched also took the tenets to a third-person
perspective. But it's Gears of War 3 and Call of Duty: Modern Warfare 3
that have absorbed the mode and aim to give it a new life in the world
of AAA games.

What series would you like to see add a
Tower Defense mode? Did I miss some of your favorites that use the three
elements? Drop your thoughts in the comments below.