A large swell of Roaches is used to push the opponent straight-away to break a wall-off and follow-up with a Zergling (with Metabolic Boost) all-in. 5-7 Roach rushes are used as all-ins; a 3 Roach Rush is defensive or feigning an attack to, hopefully, force a re-tech.
Basic Build Order
- Basic Roach-rushes are all based on one Extractor, a second Extractor would delay the attack and the Zergling follow-up.
- The start of all Roach rushes is placing the Roach Warren when your Queen is about 2/3rd done, so the Larva from your first inject pops off when your Roach Warren finishes.
Roaches also have plenty of tech to keep them strong into the mid and late game, often used as the alternative to Zergling/Baneling, acting as a strong meat-shield for other Lair tech units, like Infestor or Hydralisk. Burrow allows for quick health regeneration, and the speed upgrade along with creep will keep the opponent's ground forces occupied long enough for reinforcements, or for a different unit response if needed.
Building an additional Overlord is also important to have enough free supply to build 7 Roaches. Economic Roach defenses are after the second Hatchery is started, and should have an early Lair for fast Roach speed and Burrow upgrades and, with good Creep spread, can hold off any ground-based early pressure.
Roach Feints against Protoss, starting a Roach Warren while the scout is still in base and cancelling or making minimumal Roaches is useful for misguiding the Protoss early builds at higher levels. Roach Feints and 3 Roach Rush Speedling all-in (vs. Protoss) are somewhat useful for forcing Stalkers and overwhelming with Speedlings.