Roach Expand (vs.Protoss)
A safe expansion behind a wave of Roaches.
Basic Build Order
This is particularly strong against 4 Gates because it hits before the extra gates kick in. It can usually end the game or cause serious economic damage. With the expansion following up behind the push you will be able to grab a large economic lead. Zergling Speed should be researched, and one or two Spine Crawlers started in the main and moved down to the natural. If it is an extremely aggressive/all-in 4 Gate and it is complete before or around the time that you get there try to pick off one or two Pylons to slow down the push and save your Roaches. Hold the push and you should have a large advantage.
Versus Stalker-based play such as Blink Stalkers you will need to decided whether you can break the amount of Stalkers on the field. Depending on how greedy the Protoss is you may still be able to get quite a few probe kills. However, generally you should save your Roaches, get speedlings and drone up.
In ZvZ it is essential that you wall-off your mineral line to protect from speedling/Baneling play. You will have an excess of minerals coming out of this build - it is fine to throw down a Spine Crawler or two, and maybe an Evolution Chamber to sim city in order to survive. Due to the large amount of larava required for speedling/Baneling you should have a drone lead. Either your expansion or throw up a Baneling Nest to clear out the mass speedling and use a Roach/Baneling push. Your opponent will still be one-basing and will not likely be able to afford Roaches at all. If you stay where you cannot be surrounded and use your Banelings well then it should be an easy win.
Versus more aggressive Roach play(7 Roach Rush or 5 Roach Rush) this build will be able to get Roaches out in time to fend them off and gain an economic lead. Going for a +1 Ranged Attack Roach Speed Burrow timing attack off of 2 bases should be able to end the game.
It is extremely important that you be able to scout early aggression(speedling or regular Zergling all-in, 2 Gate) and react accordingly. Generally, if there is no gas taken you should check whether your opponent has an expansion or a large army. A proper sim city will make most rushes easy to deal with.
At the end of this build you will have 2 bases, Roach tech and not much else. If you were able to push your opponent back then scout whether he is counter-attacking or rebuilding your opponent's economy. Drone or make Roach/ling as needed. If your opponent is getting many Stalkers grab Ling Speed and threaten backstabs, but also throw up 2 or so spinecrawlers to defend. If your opponent is reduced to, or still at 1 base scout whether they are going Roaches or mass speedling. Respond with either Banelings or Roaches. Consider getting spinecrawlers.
If your opponent already has enough fighting units fall back and get your expo saturated. If he is teching hard(1/1/1 or Gateway Cyber) you can generally kill your opponent right there.
Short rush distance, protected natural, backdoors. (Steppes of War, Blistering Sands)
Long rush distance, open natural. (Delta Quadrant, Scrap Station)