Scouting in Starcraft 2

Starcraft 2 Strategy Guide --> Scouting in Starcraft 2 (you are here)

One of the most important concepts in Starcraft 2 is scouting. If you do not scout or do not know what you are looking for, odds are you will not win many games. There is a reason scouting is the first topic in my 6-part e-mail course (that you can sign up for on the left side of your screen).

What to look for when Scouting

Scouting is used to determine your enemy's game plan. Your enemy might be going for a rush, an early push, an air rush, fast tech, or an early expansion. All of these things can be detected by scouting.

When to Scout

The standard method for scouting as Protoss is to send the Probe that builds your first pylon of to scout. Terran players generally send their 9th SCV, right after it finishes the first supply depot, and the safe play for Zerg is to scout with the 10th Drone. Sometimes Zerg players opt to just scout with their Overlords, particularly when the opponent's spawn location is pre-determined by the map.

What About Pre-Determined Builds

Even if you have practiced a pre-determined build or strategy and do not plan to alter your playstyle based on what your opponent does, this does not mean you should skip scouting.

The reason for this is often players will attempt to get away with risky openers, then immediately stop that risky opener once they realized you have scouted them! For example, if an enemy gets an expansion before any units, and they see that you have scouted this fact, they will try to get up some defense in order to protect their new expansion. This will cost them resources, slowing down their macro and tech.

However, if you never scout that new expansion, your opponent may be in no rush to build units, spending all their resources on their economy and technology. This will give them a big edge over players who opted for a safer build.

What to Look For vs Terran

When playing against Terran players, the most important thing you are looking for is what their second unit-producing building is. All Terran players will build a Barracks - a single Barracks alone tells you nothing.

If their next move is to make a second Barracks, you know you will be seeing Infantry (and likely very soon!). If the Terran player was not interested in making Marines, Marauders, or Reapers, he would not build 2 Barracks.

If you see a Factory next, you know you are safe from attack (at least for the time being). The earliest attack that might happen in this situation is a Hellion push (if you are Zerg), so you have time to tech up yourself or expand whenever you see this play.

When you see a Factory next though, you do not know exactly what their move is - all that you know is that a rush is not imminent. You could be up against a 1 Barracks / 1 Factory / 1 Starport play, or they could throw down a second Starport or a second Factory.

As a result, if the Factory is their second building, you want to get another look to see what goes down as their third building. If it is a second Factory, mech is in your near future. If it is a Starport, you can bank on 1/1/1 play 90% of the time.

In HotS, 1/1/1 can include a lot of units though, so you still want to hold out to see what buildings the Terran player duplicates. Second Barracks means Infantry, a second Factory means mech, and a second Starport usually means air.

By the late game, it is not unusual for Terrans to have multiple production facilities of all 3 types if they have a good economy. Top tier Terrans will use at least 2 of their 3 production facilities no matter what their strategy ends up being.

What to Look For vs Zerg

When you are playing a Zerg player, the key early metric is the timing of their Spawning Pool. If it goes down prior to a supply count of 10, they are rushing. Additionally, one early extractor indicates Speedlings are in your near future (you only need 1 Extractor to get Metabolic boost).

If the Spawning Pool goes down after their first expansion or at 14, 15, a 16 supply count, the Zerg player is going for a traditional fast expand build. You are typically safe to expand here yourself or can even experiment with a timed push of your own.

What to Look For vs Protoss

Protoss is a lot harder to accurately scout than they used to be in Heart of the Swarm. Very early rushes will involve a second (or more) Gateway coming down as soon as the Cybernetics Core is started. While 3+ Gateways used to be indicative of an early rush, now Protoss players are able to put out significant pressure in the very early game on just 1-2 Gateways thanks to the Mothership Core, which is produced from the Nexus.

Typically, the presence of the Mothership Core early in the game is a sign of early aggression, especially at the higher leagues. While low-ranked players may get out a Mothership Core "just because", higher ranked players realize that 100 vespene gas very early in the game is quite expensive. This early vespene gas could be better spent on tech. Once vespene gas production has increased, a Mothership Core can be added for defensive purposes. As a result, an early Mothership Core usually means an early attack.

Protoss players can also be aggressive early by adding a fast Stargate or two. In order to delay this technology choice, you do not even have to get units of your own. Instead, keep a worker alive in your opponent's base until your opponent can get out a Stalker to kill off your scouting worker. Players do not like to commit to a tech tree while your scouting worker is alive because it ruins the surprise of their strategy and unit choice. Merely keeping your scout alive will delay your Protoss opponent by forcing them to get out a Stalker.

Conclusion

The key to scouting in Starcraft 2 is to look for whatever the player's second move is. Everyone has to get a Spawning Pool, Gateway, or Barracks. Do not simply go in and look to see their first building. Instead, try to hang out for awhile and see what they do next.