When Do I Expand?

The simple answer: whenever possible. Starcraft II requires you collect more resources to make more stuff. More stuff typically leads to you winning. So expand whenever you think you can get away with it.

When I first started playing Starcraft II, expansions scared me. It costs a lot of minerals to put down that extra Nexus / Command Center / Hatchery. Those are minerals that could be going toward making more units or defensive structures. It’s a scary thought, throwing an expansion out there on the map, knowing that your opponent could run by any second and blow it up.

Maybe taking your natural isn’t so threatening, but defending a third expansion meant leaving your natural or your main base open to enemy attacks. “What if they have mutas? Or voidrays? Or if they drop marines on my mineral line?” That’s right. I was so scared of counter attacks that I forgot that my opponent couldn’t possibly have access to all three. So I would sit on two bases for twenty minutes. Then, when my main was running low on minerals and necessity finally dictated a third expansion, I was too late. My opponent controlled half the map and would gladly throw away units to deny me my expansion. I was already dead, I just didn’t know it.

So when can you successfully put down an expansion? There are multiple answers, and each one applies to a different circumstance. What’s more, if you haven’t scouted perfectly, you might not even know the circumstance. That scary timing push might be coming, and even pros get stomped into the ground if they try to take an expansion while their opponent goes for an all-in. It’ll happen to you, too, if it hasn’t already. Rage all you want when that time comes. Throw your keyboard, curse the name of your opponent’s race, and write angry forum posts on Battle.net about game balance. Then sit back down and remember these basic tips for staying alive while expanding.

Expand when you’re ahead:

This is the easy, cop-out answer, but it’s still true. If you know your army outmatches your opponent’s army, then he can’t very well threaten your expansion. Just make sure you don’t lose an entire base to harassment and you should be fine (easier said than done, I know). You might think this tip is common sense, but players still seem to forget it.

It’s so incredibly tempting to go in for the kill the moment you have the slightest advantage over an opponent. Sometimes it works, but usually you just end up giving away whatever advantage you had. It’s much, much safer to take an expansion and build on your lead while your opponent scrambles to keep himself alive for the next few minutes. If you keep expanding while you’re ahead, your opponent will have to take huge risks to get back into the game, and that’s when you go in for the kill.

Just caught a pack of unsieged tanks? Time to expand.

Expand when you attack:

My last tip is applicable when you know you’re ahead, but that’s not a luxury you will often have. Maybe if an opponent’s all-in failed, or if he mis-microed his army and lost everything, but you’re not always going to know for sure if you or your opponent is in the lead. When that happens, the best time to expand is when you attack. Sure, it’s a bit more risky. Your opponent might decide to counter attack and go for a base trade, but more often than not you’ll force your opponent to defend and pin him in his own base.

While attacking, you can temporarily suspend unit production and spend those resources on your expansion. You might be tempted to spend money on reinforcements instead of another base, but remember: your opponent can reinforce much faster than you can. If you manage to keep your opponent pinned in place for a couple of minutes, you’ll have your base up and operational with practically no risk to your infrastructure.

The key to making this method of expansion work is to stay on the offensive as long as possible. That doesn’t necessarily mean you’re constantly killing things. You just need to threaten your opponent enough that he stays defensive. As long as he’s stuck in one place, you’re winning the battle. Never feel like you need to end the match with your attack, and always be prepared to run if you think you are at a disadvantage. Your buildings might not be at risk with this strategy, but your army certainly is. Be careful.

Protoss is putting pressure on the front of Zerg's natural. Good time for 'toss to expand.





Expand When You’re Out of Options:

Ideally, you would only expand when you’re in a position to defend your expansion, but that’s not always in the cards. Sometimes, despite playing well and microing your army perfectly and reading excellent tips like mine, you still find yourself noticeably behind your opponent. Sometimes, you can overcome this gap with superior unit control or a quick tech switch that gives your units an obvious advantage. Sometimes you can’t. When you can’t, it’s tempting to just surrender right then and there, but you might be able to get yourself back into the game by taking another expansion.

There’s no safe way to expand while you’re behind, unfortunately. Depending on the map, you might be lucky enough to have an expansion on hand that’s positioned in a defensible spot. Good for you, in that case, but if your opponent is smart he will expand when you do or even double expand. That way, he’s still ahead and you’re still playing catchup. To claw your way back into the game, you have to improve your economy while hurting your opponent’s. In other words, it’s harassment time. Whether you decide to use aerial units, fast units, or stealth units, keep the pressure on your opponent’s bases and stay away from his main army. Every unit is precious. You can’t afford to waste money replenishing your army while you try to establish your expansion.

Blue's mutalisks trying to take out Red's expansion. Be wary of that infestor . . . .

Conclusion

There are plenty of more methods for taking an expansion depending on your race and unit composition, but these should get you started. In case none of this advice is helpful, I’ll leave you with one more strategy. It comes to us from none other than Aleksey "White-Ra" Krupnyk: “We make expand, then defense it.” Sage words.