Roach/Zergling Pressure (vs. Protoss)
This is a timing attack designed specifically to hit at a time when the 3 Gate Sentry Expand build is weakest: just as the Nexus is finishing, or directly after.
Depending on when you stop making Drones, the build can be executed 3 different ways:
- Stop the Nexus from finishing
- Kill the Sentries
- If you decide to all-in, your goal would obviously be to end the game
 Basic Build Order
Any opening that expands and gives you 1 Gas will work. The build is commonly used when using a Speedling Expand opening.
The build starts when you have 2 Hatcheries and 2 Queens, and have just started Zergling Speed:
If you're trying to stop the Nexus from finishing, you want to stop at 21 Drones (see the IdrA replay referenced below).
If you're trying to all-in, you want to stop at around 27 or 28 and just make pure Speedlings after your initial Roaches.
If you're just trying to pressure his Sentries, and kill them or deplete their energy, you want to stop at 36, keep your Drones on gas, and expand as you attack.
This build is specifically designed to do well against 3 Gate Sentry Expand. However the earliest versions of this attack will also do well vs 4 Gate, so that is a bonus. Make sure your opponent is doing one of these builds before proceeding. If you are caught unprepared against a Stargate Opening or Dark Templar Rush, you will have no defenses and will most likely lose the game as soon as you start getting attacked.
- When Preventing the Nexus from finishing: your priority is the Nexus. Bait Force Fields with your Zerglings. Do not try to surround them if they backed their Sentries into the corner. Most likely they will realize that they do not have enough Sentries and will simply retreat up the ramp. Force them to cancel their Nexus, and try to do any damage at their ramp if possible. As soon as the Nexus gets cancelled, you should immediately switch to making only Drones until you have saturated your 2 bases.
- When going all-in: you want to kill your opponent outright here, so your focus will be their army. Try to lure their army out of position, and as soon as you can get a good surround on their army with Zerglings, take it.
- When trying to pressure: your goal here is to simply kill what buildings you can, and destroy their Sentries if possible. You are expanding behind this, so you do not need to force an engagement. The best targets here besides the Sentries are their Forge, if you can kill that, it will severely delay their upgrades going into the mid-game.
In general, your Roaches should be shooting Sentries whenever possible. If they surround their army with Force Fields to protect against Zerglings, do not let your Zerglings continually run into the Force Fields and take damage, back them away and try to kill Probes or buildings.
Since this build is a timing attack designed specifically against a certain build, there is not much room for adaptation. Unless you're going all-in, you should switch to making Drones as soon as you make 2 rounds of Zerglings. If you're going all-in, you should keep making Zerglings.
 Pro features
Small or Medium-sized Maps with a wide-open natural are perfect for this build, since it will maximize the amount of Force Fields Protoss will need to cast in order to protect your opponent's base and his units. Some notable examples of this are:
 Con features
Maps with small chokes into the Natural or a closed off Natural are not good, since Protoss can split your army using just a few Force Fields. Also large maps are generally not preferred since Roaches take so long to arrive. Some examples of bad maps are:
- EGIdrA (Z) vs. TD.Legosu (P) on Shattered Temple - IEM Americas Championship Tournament, Round 1 - Game 2 - IdrA shows a perfectly executed fastest version of this attack, stopping at 21 Drones, and making 8 Roaches before attacking. Legosu only has 2 Sentries, and is forced to cancel his Nexus. IdrA then outmacroes him and takes an easy win.