This might all be common sense but I felt like writing it so I'm posting it anyway :p I hope people find it useful.
A game of SC2 can be quite unpredictable, with the momentum shifting to one side in mere seconds. We often see that one player gains a slight lead just to throw it away due to bad decision making. This short article will attempt to discuss possible approaches to take when the game is favoured for one player. For the purpose of this article, we will assume that both players are equally skilled and the game is distinctly favoured for one player but not decisively so. That is, one player has a marginal lead.
How to determine if you are ahead or behind
At any point in the game, you should be choosing strategies that maximize your chances of winning. Being a game of incomplete information, knowing the current state of a game helps you make better choices. Let’s say you attacked with your initial army earlier and lost everything while doing minimal damage. If you don’t take this into consideration and follow this up immediately with another full-out frontal assault, then you have made a terrible decision. You were behind in army size so attacking was out of the question.
When trying to determine where you stand, you need to evaluate two variables: economy and army. Of course there are more variables in play (map control, tech, mobility, etc.) but they all boil down to economy and army in one way or another. Look at the number of bases and worker saturation for determining who is ahead in economy and the prior engagements for army. If you are ahead in either army or economy but not behind in the other, then you are ahead.
How to play when you are ahead
A wise Dan once said, when you are ahead, get more ahead. What this means is when you are ahead, get more ahead in economy. This means you should secure another base or increasing worker production. This economy lead will translate into an army lead in a few minutes. Basically, if you have the option of getting paid $10 now or $30 five minutes later, then always take the $30! Also, maximize your chances of winning by investing some of your lead into more defenses which shut down harassment play by your opponent. At higher levels of play, this move can be exploited (especially by Zergs) but for the majority of people who are reading this article, I would recommend doing so anyways.
Special note: In match-ups such as PvP, expanding is very risky so it is not recommended that you expand with a marginal lead. Instead, you can build a few more probes while launching the counterattack if you are not fully saturated.
How to play when you are behind
This is probably the more interesting topic for many people. When you lose your initial army, what do you do? Playing it safe and standard won’t cut it anymore. You need to get an advantage back by taking risks. I will analyze a few common routes people take in this situation.
1. Turtle in your base
Some people become too afraid to move out after they’ve lost some units and turtle until they max out or their opponent rams their army in. This relies on your opponent playing poorly and won’t win you many games against experienced players. You will hand over any chance you had at coming back if you turtle in your base.
Verdict: Not recommended
2. Expand (or build more workers)
One way to catch back up is to get an economic advantage or at least keep it even (since your opponent will likely expand himself). If you are 20 supply to 30 in army, that 10 supply difference becomes less significant when it’s 100 to 110. There are two variations to this method: hidden expansions and regular expansions. Since hidden expansions are harder to defend, they are more risky and should be used when you are too behind to just take a regular expansion. When you are expanding, you should avoid engaging your opponent’s army unless you are sure that you can come out ahead. Trading armies is not favourable for you at this point. Use small scale harassments to distract your opponent and buy time while you get your economy running. You can also tech to undetectable units (dt, banshee, burrowed blings, etc) to buy time. Zergs also have the option of droning hard in order to catch up in economy.
3. Go all-in
If you lose a bunch of workers to harass and you know that you are far behind in economy, you may choose to go all-in by attacking with everything you have. The chance of this working is slim but playing a standard game or trying to catch up in economy may be impossible at this point.
Verdict: Not recommended except in situation described above
4. Play aggressively
If you are not too far behind in army with a similar econ or even in army with a slightly worse econ, then you may choose to start playing very aggressively. Split up your army and gain small advantages in each battle to chip away at your opponent’s lead. This requires superior multitasking but it’s a good way to disrupt your opponent’s rhythm and force a mistake.
There isn’t a “right” way to play SC2. Many factors such as style, your opponent’s tendencies, or even your mood that day can influence the way you play. The only requirement is that you increase your chance of winning. The methods above are what I find works best for me. Some people may find that other methods works better for them.
Please let me know what you guys think! If you have other ways of playing when you are ahead or behind, feel free to post here for discussion.