Lesson 6 of 14

An army you can actually use

Units you own are not units that are fighting. Turn production into an army that is doing something.

Lesson
6 of 14
Watch
A written lesson, no video
Practise
A checkpoint і a plan for your next game

Minerals in the bank do not win fights. Units standing at home do not win fights either. Only units in range of something win fights. This lesson shows you where your army gets stuck on the way there, and how to find the jam in your own games.

What you will learn

  • The three places your money can be, and why only one of them counts.
  • The six step production line, and how to spot which step is jammed.
  • A two second check of bank and buildings that tells you what to buy next.
  • How to measure how much of your army actually fights.
  • How to wall so your own army still gets out.

Three places your money can be

At any moment, everything you have earned sits in one of three places. Only one of them can kill anything.

Where it is What it is worth in a fight right now How fast it moves on
In the bank Nothing As fast as your production can spend it
In units at home Nothing As fast as they can walk
In units in range of something Everything This is the end of the line

Most losses that feel unfair are a player with more total value than their opponent, sitting in the wrong two columns.

Macro is a production line

Think of macro as six steps in a row:

  1. Earn income.
  2. Build production.
  3. Keep supply ahead.
  4. Make units.
  5. Get them out of the base.
  6. Use them in a fight.

It works like an assembly line. A jam at any step stops every step after it, and every step before it piles up. Supply blocked? Your income keeps coming, your buildings sit idle, and no units reach the fight. Your bank going up is how you notice.

The line, and what a jam does to it
income produc-tion supply units out ofbase in range these keep earning these three get nothing the jam

Every step before a jam piles up, every step after it starves, and a rising bank is how you notice.

Two things follow, and both change how you spend your attention.

  • Speed on a late step is wasted while an early step is jammed. Perfect micro does nothing if half your army is still walking out of your base.
  • An early mistake ripples forward. A supply block at five minutes is an army that arrives late at seven.

So spend your attention on the jam, not on the step you enjoy. Early in the game, that is almost always workers and supply. Later, it is getting units out of the base and into position.

The two second check

Look at your bank and your production buildings at the same moment. There are only four cases.

Bank Buildings What it means What to do
Piling up Busy Your production is too small for your income Build another production building. A gateway or barracks is 150 minerals and raises your ceiling for the rest of the game.
At zero Idle Your income is too small Workers, or a base
Piling up Idle You are supply blocked, or not looking Fix it now. This is the one that decides games.
At zero Busy Nothing is wrong Spend your attention somewhere else: scouting, the army, harass

Make it a habit. Every time your army is walking somewhere, glance at the bank and your buildings and name the case.

How much of your army actually fights

Owning forty supply of army is not the same as fighting with forty supply of army.

Call uu the share of your army that is in range of something during a fight. What you are really bringing is

Aeff=u×AA_{\text{eff}} = u \times A
(1)

and uu is lower than you think. A column walking into a choke might have a quarter of its weapons in range. An army that arrives in two halves fights the first half alone.

Worked example: the bigger army loses

You have 30 zealots, which is 3,000 minerals. Your opponent has 20, which is 2,000. You should win easily. Now you walk yours up a ramp, so only eight are ever swinging at once, while theirs stand in an arc at the top with fourteen swinging.

You Them
Minerals in the army 3,000 2,000
Share in range about 0.27 about 0.70
Minerals actually fighting about 800 about 1,400

You are losing the fight almost two to one while ahead by half on paper. And because the units that die first stop shooting, the gap gets worse every second. Production gets you the 3,000. Only positioning makes it fight like 3,000. Lesson 4 shows why chokes, arcs and surrounds decide this, and the Flux Lab lets you count it.

Five habits that keep the line moving

  1. Queue one unit at a time. A queued unit costs the money now and arrives no sooner. The money sits idle in the queue for nothing.
  2. Build supply on a rhythm. Supply is the jam that costs the most, because it stops a fully funded line. With five production buildings running, you need new supply every 40 seconds or so.
  3. Put your production where one screen shows it all. You want to reach every building in one second, not a nice looking base.
  4. Rally to where you want the army, and move it forward before you need it. Walking time is a step of the line, and the one everyone forgets.
  5. When your bank goes up twice in a row, build production, not units.

Walls: placement that helps the line

Buildings are also terrain, and you choose where they go. A good wall does two jobs: it stops their units, and it still lets yours out.

  • A full wall keeps small units out completely. It is strong against an early zergling rush, but your own army cannot leave either.
  • A wall with a gap one unit wide is usually better. Put one sturdy unit in the gap. The enemy has to come through one at a time, and everything behind the wall gets to shoot at the one that does. That is the ramp example above, working for you.
  • Leave room behind the wall for workers to repair or for units to stand and shoot. A wall with no space behind it is just a line of buildings.
  • Take it down when it is in your way. A wall that saved you at four minutes can trap your army at twelve. If your units queue up behind it, it has stopped being a wall and started being a jam.

Common mistakes

  • Counting the army instead of the fight. Before you attack, count how many units will be in range in the first five seconds, not how many you own.
  • Queueing five units to save clicks. You have spent 250 minerals that could have been anything for the next minute.
  • Buying units when you need buildings. A rising bank with busy production means you need more production.
  • Leaving new units at the rally point. Units at home are the second column of the table: worth nothing.
  • Perfect micro, late reinforcements. If half the army arrives after the fight is decided, the micro was spent on the wrong step.

Practise

Then the replay drill. Open one of your own games and do three things:

  1. Every time your bank passes 500 minerals, pause and name which of the four cases you were in.
  2. Take one fight you lost. Pause at the moment of contact and count how many of your units are in range of an enemy. Divide by how many you brought. That is your uu.
  3. Find one moment where units sat at your rally point for more than twenty seconds while a fight happened somewhere else.

Fix the worst of the three in your next five games.

Checkpoint

Checkpoint

  1. Your bank is climbing and every production building is busy. What do you buy?

  2. Your bank is climbing and your buildings are idle. What is the most likely cause?

  3. You have 3,000 minerals of army against 2,000 and you attack up a ramp. What number decides the fight?

Credits and sources

Built on Game Theory with Application to Starcraft, taught at UC Berkeley in spring 2009 by Alan Feng, Anthony Chen and Sherwin Mahbod, as its week 6. The teaching on this page is written in our own words. Not affiliated with UC Berkeley or anyone named here; if something should not be here, tell us.

All sources for the course