Roach

The roach is a zerg ground unit in StarCraft II. It is strong against Hellions, Zealots, and Zerglings. It is weak against Marauders, and Immortals.

Overview
The roach is a particularly tough zerg breed due to its high speed regeneration ability.

Attacks
Currently, the roach is a ranged unit, giving it added utility at choke points. It has possessed the ability of attacking both air and ground units in the past, though is currently ground only. The roach rises slightly when it attacks. It also has a melee attack that it, like the hydralisk, performs at close range for the same damage as the ranged attack.

Strategies
A roach's regeneration is quite powerful, and it can often regenerate faster than it takes damage.

Roaches work well in small skirmishes rather than large encounters, because they are vulnerable to focus fire. A single roach can defeat a single stalker due to its high regeneration, for instance, but several stalkers can defeat several roaches with focus fire. Groups of s can counter roaches as well.

Roaches are also vulnerable to sustained damage. Roaches are strong against opponents that attack slowly and do low damage per attack, such as zealots. Karune reports that "in theorycrafting, they seem stronger than they actually are, although specific units must be used to counter them, or additional micromanagement time be taken to defeat them. s, stim packed s, stalkers, immortals, s, hydralisks, and any air to ground unit, are all effective at killing Roaches with a little micromanagement."

A roach/baneling combo is very powerful against terrans, as the roaches will soak damage, enabling the banelings to get close to the enemy and deal their high damage attacks.

Zerg vs Zerg
Roaches and zerglings are used early in zerg vs zerg matches. Compared to zerglings, roaches are a more defensive unit. Cost for cost, roaches win against zerglings in chokes but lose in open areas. Later in the game, numerous roaches can defeat numerous zerglings even in open areas.

As a game progresses, a roach/hydralisk combo can defeat a zergling/mutalisk combo.

Development
In April 2008 the roach regenerated at 15 HP per second (25 hp/second with Organic Carapace). A roach could heal fast enough to retain approximately 50% of its hit points if hit by a psi storm, and over 80% of its hit points after its regeneration has been upgraded. The roach's regeneration rate appears to have slowed as of April 2009.

As of May 2008, due to a bug roaches were not affected by the Dark Swarm's secondary ability of preventing units inside it from firing. Dark Swarm was later removed from the game by October of that year.