StarCraft II - Units of the Zerg
Swarming around like angry bees, the Zerg of StarCraft II have the same
effective tactics that they do in the first game -- dominant basic
troops, strength in numbers, and fantastic raiding abilities.
The Zerg have the least amount of changes to their basic gameplay, but
the macromanagement of your base and use of abilities on units like
Infestors and Banelings is essential to turn the tide against players
that use abilities of their respective races.
Using slow, potent units is always troublesome, but the Zerg can make their lives easier by spreading the Creep. Spreading Creep only enabled building production before, but it now gives all Zerg ground forces a sizable speed boost. Zerg production still revolves around the Hatchery, and it produces Larvae of which every unit except the Queen originates from. Larvae is produced at a set rate from each Hatchery, and once 3 idle larvae are at the hatchery, no further production will occur until the current ones are used. This enables the Zerg to stockpile larvae until a key building finishes, and then produce 3 of that unit!
But what units can you produce in the sequel, you ask? Let's break down our favorite aliens' weapons of destruction.
Land Combat - Might is Right.
They slice, they dice, and they explode. Such creative aliens!
Banelings - The Zerglings are sick of being the rank and file sacrificial grunts, and decided to take it to the next level. For a piddly 25 minerals and gas, you can turn a Zergling into a real suicide combatant. Banelings are slower than Zerglings and still only have 35 HP, but upon reaching their target they explode violently for 20 damage in a fairly wide area of effect. They also do a bonus 15 damage to light units such as workers, Zealots, and Marines.
The main reason to use these is to demolish a heavy line of Zealots, Zergilngs, or Marines, and if they reach their targets, they do just that in spectacular fashion! Detonation doesn't damage your own units, and if they're killed prematurely, they don't explode at all. They can burrow just like their predecessor, and surprise those on the surface with the same explosion with no risk of being killed first! A devastating unit... if it reaches its target. You can upgrade the speed of these at the Baneling Lair, which only requires a Spawning Pool to build. You can get these relatively early and they have a special attack versus buildings, making them highly potent against building wall-ins to break those pesky techers.
Roaches - Like the Roach itself, the Roach is incredibly durable. Sporting an impressive 145 HP and 1 armor, the Roach is your ideal front line tank-type unit. They deal a fairly high amount of damage, but have one of the lowest attack speeds in the game which makes their offensive potency quite low unless microed to burst single targets down instantly. They only cost 75 minerals and 25 gas, and shockingly, only 1 population! All you need to produce these is a Roach Warren, which is the next step after a Spawning Pool.
When burrowed, they regenerate HP at an amazing rate. Several upgrades exist, which upgrade their movement speed, regeneration speed, and even give them the ability to move while burrowed! Durable as they are, they are considered Armored units, which have several potent counters. Massing these can be a winning strategy early, but typically ends in colossal failure. Use them to support your more damaging units, not to dish out the damage themselves!
Hydralisks - Firing spines at a high rate, the Hydralisk is your bread and butter ranged unit. It does high damage from a safe range, now doing 13 damage a shot, and no longer carries the old penalty versus smaller units that it did in StarCraft. Unfortunately all of this power comes with an increased cost, the Hydralisk now costs 100 minerals, 50 gas, and 2 population. They've also lost their speed upgrade, making spreading the Creep that much more essential. They still have the range upgrade though to make them the most versatile and dangerous ranged unit in the game, and massing them is still somewhat viable against opponents of moderate skill. Most counters to Light units can't even reach the Hydralisk to begin with, but spells demolish their puny 80 HP count. They also require a Lair before you can build the Hydralisk Den, making them a little slower to reach the battlefield.
Ultralisks - Towering over everything, the Ultralisk is a 600 HP behemoth. With its massive blades, the Ultralisk now deals splash damage in a wide radius with every attack. This comes at a cost of raw damage though, and the Ultralisk only deals 18 base damage with each attack. When taking it to a building or defensive structure, the Ultralisk forgoes the blades for a good ol' fashioned headbutt, which deals massive damage and brings down buildings at an absurd rate. These units still have the potential to be the highest Armor units in the game, shrugging off Marine fire and Zealot blades to almost no effect.
Sadly, with all of the counters to Armored units in the game, the Ultralisk's toughness really doesn't shine on the battlefield to nearly the same extent it did in the first game. Immortals, Marauders, and Hydralisks will all bring down an Ultralisk or two with little to no problem or casualties. Ultralisks take on the role of a threatening support now, rather than being a semi-threatening HP sponge. If an ultralisks gets good positioning on a force, it can do massive damage, but it's now so big and lumbering that it trips over your own army trying to get into that position, and by the time it does, it will likely be almost dead through focus fire. Hopefully this unit receives some more love after release.
Air and Support - Completing the War Machine
Zerg support is outstanding, but requires heavy micro to survive due to their low survivability
Mutalisks can go toe to toe with most anti-air due to their splash damage, and can out run that which it can't kill aside from the Protoss Phoenix. Achieving air superiority forces the opponent to forever fear you sweeping in and blasting his or her workers to pieces in quick succession, and then flying out with zero casualties yourself. This is a nightmare to deal with and forces your opponent to build anti-air defenses and extra workers, which can dramatically boost your chance of success on the ground. Keep these units away from Thors and Marines, and be careful of Hunter Seeker Missiles, Psi Storms, and Fungal Growth, all which can disable you or turn your Mutalisk cluster into a bloody mess. These do not have an evolution anymore, they are one form and one form alone.
Corruptors - Heavy Anti-air units, these clock in with a hefty 2 armor and 200 hit points while only costing 50 more minerals than a Mutalisk! If your opponent is going for Capital Ships or other massive air type units, these are the Zerg's immediate go-to unit. These deal fantastic damage at a fairly good rate to opposing massive units, but do not get any kind of bonus against armored or light. This gives them a distinct weakness to Void Rays and Vikings since they are armored units themselves, and those shred Armored targets! When the skies are clear or you get an opportunity, you can use the Corruption ability to disable a building for 30 seconds of an opponent's. If you come out on top of a battle, using this ability will give you the ability to create reinforcements while sealing that chance off for your opponent, guaranteeing a victory soon.
Brood Lords - Flying symbols of doom, the Brood Lord is an evolution of the Corruptor that has a final cost of 300 minerals, 250 gas, and 4 population. They launch broodlings at targets that deal 20 damage on impact, and then the Broodling will run around attacking units for 4 damage a hit (and benefits from Melee-type upgrades). The main reason to build these is the Broodlings--these units will soak up fire and mess with the targeting of units not under direct orders of your opponent. The Brood Lord also fires these from a safe distance, giving them the unique ability to siege targets from the air with zero opposition from ground based defenses. These are quite slow though and need to be escorted carefully due to their cost. They are tough as nails at 275 HP and 2 armor, but with no ability to retreat you better be able to win the battle if it comes to you!
Infestors - Burrowing Casters, they sneak around the battlefield only to come up and latch onto targets with their mind controlling tentacles or spew vile Infested Terrans or Fungal Growth. They have a large collision size and stand out on the battlefield, so keep them safe or they'll be splattered in no time. They cost 100 minerals, 150 gas, and 2 population and can move while burrowed without an upgrade. You do still have to research burrow though!
Â Infested Terrans - A simple 25 energy cast that spews an egg at a targeted area. When it hatches, a 8 damage Infested Terran spawns that guns down nearby units with a rifle. It can hit land or air, and this ability can be spammed very quickly. The Infested Terrans move very slowly and have a limited lifespan, so you can't amass them for a strike. They have to be deployed to the hot spot so they can serve their purpose and die once more.
Â Neural Parasite - Grabs a unit from long distance and takes complete control of it. You can cast or attack anything you like with it, but if you move too far from the Infestor, the link will be broken. Can be devastating if you can keep the Infestor alive, and can target a strong unit that will turn the battle in your favor almost immediately with. This can only target land units unfortunately.
Â Fungal Growth - Blasts a target area with goo that latches onto targets both on ground and in the skies, holding them in place, revealing stealth, and dealing 36 damage over 8 seconds. It only costs 75 energy and has no cooldown, unlike the Psi Storm of Protoss. Incredibly useful versus air harassment and anytime you are planning flanks and surprise attacks, this basically forces your opponent to stand and fight or lose that portion of his army affected by this. A game changer when cast effectively.
Queens - The only unit not spawned from larvae, you can create these from your Hatchery once your spawning pool is complete for only 150 minerals and 2 population. The Queen has a slight attack against ground and air targets, and has zero weaknesses to be exploited by raiding units. They're fairly tough, but also very good targets for opponents to target. They move well on Creep, but don't even bother taking them off it. They move like diseased livestock off the Creep. This is your only source of anti air before a Lair!
Â Spawn Larvae - The ability you build this unit for, it spews 4 eggs onto a target Hatchery. After 40 seconds, the eggs hatch and 4 additional larvae are spawned instantly at the target Hatchery. This ability can be spammed constantly at one hatchery for each queen you build, and should be done! You can go beyond the limit of 3 larvae using this ability, and instantly produce 7 combat units if you had 3 idle already when they pop.
Â Spawn Creep Tumor - Your primary way of spreading the purple stuff, the Queen will run over to an area and drop one of these bad boys anywhere there is Creep already. It costs the same as Spawn Larvae at 25 energy, so if you don't mind sacrificing a turn of larvae spawning, you can do this instead. Generally you only need one of these since each tumor can spawn another tumor, and this chain will continue until the most recently tumor created is killed. Once that tumor is killed, you'll need to use another shot of this ability to create another tumor that can propagate more tumors. These also give sight in a fairly wide radius and are considered burrowed/invisible to most units, enabling you to spot early attacks and scout incoming trickery. Creep is essential for a lot of good tactics and will contribute to victory or defeat due to the speed boost, so use this!
Â Transfusion - A simple 50 energy ability that heals a targeted unit or structure for 150. Best used on defense on your Spine Crawlers, or on badly damaged Mutalisks as you raid your opponent, generally you won't have the energy to use this if you're making good use of your Spawn Larvae ability. But if you fall behind, this is there when you need it most!
Overlords and Overseers - Your basic Overlord hasn't changed except for one crucial weakness--they can no longer detect stealth units at all. They exist only as flying scouts and food sources. Fortunately the Overseer evolution, available at the Lair, covers up that weakness, gains a great speed boost, and gives it a unique ability called Changeling. The Changeling will not be shot at automatically by the enemy, and will change into one of their units and colors to blend in. You can use these units to scout without being seen, and gain precious intelligence. Since Overseers have no other use for their energy, make good use of this! They aren't cheap at 50 minerals and 100 gas per evolution, so make them count and guard them well.