- 0 – Supply at Choke
- 11 – First Barracks at Choke, place carefully (an addon needs to fit)
- 13 – Gas
- 15 – Orbital Command ~ Get 1 or 2 marines to fend off lings.
- 16 – Supply Depot (complete wall with this if required).
- 17 – Engineering Bay and a Reactor on first rax.
- 18 – Second Barracks
- 20 – Third Barracks
- 21 – +1 Weapons Upgrade
- 22 – Supply Depot
- 25 – Tech-Lab on second Rax
- 30 – Reactor on third Rax
Let's break it down. The number on the left is how much supply you have used. You will start the match up with 6/10 supply. That is, you'll being the game with 6 SCVs and one Supply Depot (+8 maximum supply) plus one Command Center (+2 maximum supply) giving you a maximum of 10 supply. You'll want to always be building SCVs until you can get three on every mineral patch and 2-3 on every Vespene Gas geyser. As you do, you'll start using up your available supply. The instructions on the right let you know what to do when a certain supply point has been reached.
When you create 4 more SCVs in addition to the 6 you start with, you'll be at 10/10 supply. You need to increase you maximum supply to be able to build any more units. Order an SCV to build a Supply Depot (+8 maximum supply), preferably on the ramp leading into your base so you can create a choke point for any incoming armies. When that is done you will be at 10/18. Keep pumping out SCVs and when the next one rolls out (11/18), have it build a Barracks next to the Supply Depot you just created. While that is in progress, two more SCVs will roll out of your Command Center eating up two more of your supply and bringing the total to 13/18.
At 13 supply, you'll want an SCV to build a Refinery on a Vespene Gas geyser. Why 13? Why not 6? Why not 20? Different build orders have different timings depending on what armies you want to field, but it's generally unwise to collect gas at 6 supply as you will need SCVs to focus on collecting minerals to pump out a few early Marines and additional buildings. Marines don't need gas to create and you'll need to get some kind of unit protecting your base as early as possible to stop a Speedling Rush, Zealot Rush or Marine Rush from your opponent. On the other hand, most units after the Marine will require gas and you'll want to start collecting it sooner rather than later. Especially if you are trying to form a bio ball of Marines and Marauders to go rip up the other guy's base before they can get up the defenses to stop you. And you will need gas for Armor/Weapon upgrades that are key to this build.
The SCV building the Refinery will start collecting gas from it automatically unless you've queued another order for it. Don't forget to put your next two SCVs on the Refinery. That will bring you to 15 supply.
By the time you get to 15 SCVs, your Barracks should be done which allows you to upgrade your Command Center to an Orbital Command. This will not tie up an SCV and when done will allow you to call down a super-SCV (aka Mule) to collect minerals at a faster pace and to use a scanner sweep to view what your opponent is doing without sacrificing any units. Also, since the Barracks are done, immediately build 1-2 Marines to deal with any early attacks and take out any of your opponents scouts. Each Marine will add one to your supply total.
At 16 build a Supply Depot next to your Barracks and the first Supply Depot you created at 10/18 (leave room for the Barracks Addon to fit) to wall off your ramp entirely. This wall of buildings will buy you time against incoming attacks while you continue with your build order. Don't worry about the Suppy Depots blocking your exit out of your base. You can lower them into the ground to let your forces pass and the raise them back up.
The strategy behind the rest of this build is on Team Liquid's 3 Rax BO page, but here are some things to watch out for with any build:
- Don't get supply blocked. That is, always have a Supply Depot ready to build before you max out. Notice how the build order has you create a Supply Depot at 16/18 and not 18/18? By the time it's done building the Supply Depot, you'll probably be at 18 supply and need your max supply increased. Build orders are designed to have buildings finished right when you need them. Also, keep creating Supply Depots every time you get close to max. Some build orders assumed you are doing this and don't tell you to, just like they assume you are always building SCVs until you have the max on each resource field.
- Assign an SCV to repair your Barracks and two Supply Depots at your choke point if attacked. You can also place your two Marines behind the buildings to attack from short range without getting attacked back by Zerglings or Zealots.
- Use the MULE's from your Orbital Command to gather minerals quickly, but save your OC's energy for an occasional sensor sweep of your opponent's base
- Send out an SCV/Probe/Drone to scout sooner rather than later. Some players send one of their initial 6 workers, some wait until there they have build a supply unit and a building capable of pumping out combat units on the theory that there is nothing to see at your opponents base until then anyway.
For Protoss players, build orders are much the same except probes can initiate a building, then do another task while the building warps in. Unlike SCVs, they are not tied up while the building completes, so the build orders are little different to reflect that.
For Zerg players, build orders are a little wacky since your drones sacrifice themselves to become the building so you'll see supply numbers drop and then come back up in their build orders. There is also a common tactic of using a drone to create an Extractor on a Vespene Gas geyser, creating two Zerglings, then canceling the Extractor before it's finished to get the Drone back and be at 11/10. Those build orders will state that explicitly.