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Thursday
Feb052009

UC Berkeley Starcraft Class, Week 2

Week 2 of the class was better than week 1 because most of the administrative stuff was out of the way so more time could be spent discussing StarCraft itself.

This week was about units. Professor Feng started by explaining that units are your eyes, ears, and hands in the game. Units give you vision through the fog of war (eyes) and are they are what you use to perform actions such as attacking, repairing, building, moving (hands). What he said we might not realize is that they are also your ears. He mentioned one match where the famous player Boxer put an SCV kind of near some minerals to scout, but it was actually the sound effect for gathering minerals he listening for, rather than the sight the SCV provided.

The next topic was something I refer to as local imbalance, though that term wasn't used in class. Explained in my terms, a game is supposed to have global balance (Zerg vs. Terran for example) but it's supposed to NOT have local balance, or it would be too boring on homogeneous. StarCraft has massive local imbalance amongst units and that is a very good thing.

One example was siege tanks. The longest range Protoss ground unit is the Reaver, with range 8. Zerg have lurkers of range 6. But Terrans have siege tanks with range 12(!) when in siege mode. This is a massive "imbalance" in that it gives you an advantage the other sides don't have. That is not to say there is any design problem (it's a strength of the design, not a problem), but it is to say that you have to recognize what exact situations and unit combinations are completely slanted in your favor so you can play to get into those situations.

Feng then asked us to name any Terran melee unit. Firebat? No, it's splash damage. SCV? No, they can't attack under Dark Swarm. There are no Terran melee units, he said. This was just to show that local imbalances swing the other way if you need to fight on the ground under a Dark Swarm.

Next, he asked us "What unit are you afraid of from Protoss if you are playing Terran?" Someone immediately yelled out Carriers. He then explained how good a cloaked Wraith would be against Carriers. Of course, your opponent knows this so your opponent has Observers to reveal the cloak of your Wraiths. He then examined the Medic's abilities, explaining the function of Flare. Flare blinds units and also turns off their detection abilities. Putting all this together, he said, you could use Medics to Flare all the Observers, then attack the Carriers with your cloaked Wraiths.

Here is a video of Boxer doing just that. (Is this a Boxer appreciation class?) Notice that he actually sends in just one Wraith initially, as a test of whether the Carriers can see it. They can't so he sends in the rest.

 

Feng then talked about damage types and sizes. As you probably know if you've played StarCraft, units are classified as small, medium, or large and attacks can have classifications of concussive (good against small, bad against large), explosive (the reverse), or normal (full damage vs all sizes). He then pointed out that Zerg's Sunken Colonies deal explosive damage and asked us to think about the implications. Most early units are small, while later game units tend to be bigger. That means Sunken Colonies actually increase their effectiveness as the game goes on. (Yes I know that's a simplification because of things like air units and siege tanks, but you get what he meant.) He said we should note though that units can upgrade their damage (zealots for example), while turrets can't (they only get a defensive upgrade).

Feng then asked us to think about how seeing some of the enemy's units gives you information. Not only what they attack you with but what they DON'T attack you with. A specific tell to look for is how much gas their units cost. You usually have some idea how much gas the opponent has, and if he sends wave after wave of units that don't cost any gas, then you can guess what's next. Feng asked, "If your opponent sends wave after wave of Zealots at you, what do you think is next?" One student answered "more Zealots" and I thought to myself that would make a good Rose player in Street Fighter Alpha 2.

Next, Feng asked us what would you do if you've reached late game, the map's minerals are mined out, your only units are a single drone, some overlords, and one defiler. Your opponent has one Wraith. Furthermore you have only 47 minerals, and 38 gas. One student said "I would type gg," which Feng accepted as usually a good answer in a case like that. But he showed a video of just such a situation.

The Wraith attacked the Drone. In moments, it would die. Before it did, the Zerg player put the Drone inside an Overlord, just to buy a little bit of time. He then used the Defiler's Dark Swarm many, many times in a row as a way to transport the Drone safely to a gas mine. With swarms everywhere and temporary protection from the Wraith, the Drone mined enough gas to build Scourge, then used the Scourge to kill the Wraith. This made the game a draw instead of a loss. Here's the video:

Someone asked how this happened and Feng explained that the Zerg player also had a pack of Ultralisks, but they were worthless because the Terran could fly his buildings around, preventing the Zerg win. The Defiler actually consumed one to keep up the Dark Swarm barrage.

Yosh then took over and showed us several examples where a player attacks in a way that is designed to get an advantage but is specifically not intended to win the game. The first was a reaver drop with a shuttle, 1 reaver, and 1 zealot. The shuttle landed the enemy's base right by the minerals, and adjacent to the enemy's one siege tank. The tank went down almost instantly, and the reaver tried to kill as many SCVs as possible while the Terran player scrambled to move them to safety. I cringed as each SCV died, because losing any of them, not to mention all the time lost where none are mining, is deadly in a game of exponential economy. Several died, at least 5, before the Terran was able to surround the reaver with SCVs and kill it.

Yosh then asked us if the Protoss player intended to win the game with this move. It's certainly possible to, and it's been done before. But we know that he really didn't because at the same time, he was building an expansion. Yosh said that if the Protoss player was serious about winning right then and there, he would have invested in more attacking units, send those too, and not put the resources into expanding. The player's actual choices were very good though. The attack did serious damage to the Terran while leaving the Protoss player with good economy.

The next example was a Protoss player who sent 2 corsairs around the map. What was his objective? Obviously not to win the game on that move, but to scout. It wasn't only scouting though, Yosh explained. The corsairs were able to fight a couple overlords, so the Protoss player gained more than just scouting information. Also, the Protoss player knows that one of Zerg's strong moves in this match is to build a bunch of Mutalisks. The Corsairs were really looking for a Spire to see if the Mutalisks were coming or not. If they *were* coming, then having corsairs is a already a headstart on countering the Mutas, so he thinks that's what the Protoss player was gambling for. No Spire was seen, but it seems that the Protoss player's actions were sound and his gains were good.

Next he showed us an example of the Mutalisk stacking bug. By making a group of Mutalisks with one (far away) Overlord in the same group, a bug in the StarCraft game engine makes the Mutalisks stack even more exactly on top of each other than they normally would. This also lets them attack simultaneously, as if it's one big attack. Yosh showed us a match where a Zerg player sends his stacked Mutas to the Terran base. Does he expect to win off this attack? No he doesn't. What he finds is a pretty well defended Terran base with turrets.

The Zerg player circles the Mutas around the base, going for containment. The Terran will not be able to leave the base while the Zerg player expands to a second (or even third) base. But as the Mutas fly around the Terran base, they find an opening and are able to take out a few Terran units. The match goes on to show some cat-and-mouse play with the Mutas, some are lost, but the point is made. They harassed, they contained, they destroyed some units, and they allowed the Zerg player to expand without trouble.

Yosh's final example was a match where the Terran player sent 3 Vultures and 3 Siege Tanks to the enemy Protoss expansion base. Before doing this, he scouted and gathered enough information to believe that attacking early would probably be favorable to him. He did not know exactly what was in the Terran main base though (which was up a ramp). Anyway, he sent the attackers, clearly having Vultures in assigned to one hotkey and tanks to another hotkey. As he arrived, the Protoss player pulled all his expansion probes away, up the ramp to safety while mobilizing 4 Dragoons to fight the Terran units. The Terran player quickly laid spider mines everywhere to control space around the expansion, then attacked the Dragoons. The Dragoons were forced to retreat up the ramp to the main base. The Terran was then able to destroy the expansion base.

Yosh said the whole thing was executed very well by the Terran, but he pointed out two improvements the Terran might think about. First, if he had driven his Vultures ahead quickly at the start of the skirmish, he could have laid the spider mines in a way that would have basically forced the Dragoons to get hit as they retreated. The vultures would then have been able to actually kill some of the Dragoons. Second, Yosh believed that it would have probably been a better idea to bring 3 SCVs to the fight. At the very least, these SCVs could repair the tanks during battle. They can also act as a wall to buy for the tanks as the slow dragoon shots hit them (or float around them due to strange bugs with Dragoon shots). Also, the SCVs could then stake out the territory by building turrets or whatever else.

Anyway, the Terran player didn't bring SCVs and what he did after the battle, I found very interesting. He left. That's right, he just turned around and went back to his base. I have spoken much about "pressing the advantage," but in this particular situation, it does seem that leaving was a smart choice. Yosh referred to this as "accepting the advantage." The Terran could have pushed up the ramp and tried to win right there, but it's really uncertain how that would pan out. He could have lost all those units that way, or he could have gotten lucky. He didn't have the main base scouted and even if he did, 4 dragoons and a ramp can go very wrong for you. Instead, he let the game play out, knowing that they would end up in a 3 base to 2 base situation, with Terran advantage.

Finally, Feng took over again and showed us a video about how 3 Marines can cleverly avoid all damage from a Lurker by making the Lurker attack, then moving to avoid the linear attack, then briefly firing and repeating. This is very, very difficult (impractical in a real match to do it to the degree shown in the video) but it shows a concept you can use a little bit here and there in a real match.

He said that studying small details of the game like this is very important and it's how people in the class can contribute to the StarCraft community. As parting words, he gave an offer. Sometimes when a Dragoon shoots at an SCV, the shot misses completely. Maybe it's something to do with the SCV turning at just the right moment, he doesn't know exactly. He said if someone can show a way to make a Dragoon miss at least 50% in this situation, that he will give that student a passing grade for the entire class.

That's all for this week, and it was a lot. Did you actually read it all?

Reader Comments (67)

Yeah, read it all, highly entertaining read! Can't answer the SCV miss% question, though.

February 6, 2009 | Unregistered CommenterRobert August de Meijer

sure, and I'll give the link to some other people^^.

February 6, 2009 | Unregistered Commentershoto

Does the High Ground vs Low Ground hit penalty (70%) and the Cover hit penalty (70%) stack?

February 6, 2009 | Unregistered CommenterInterWill

Does the High Ground vs Low Ground hit penalty (70%) and the Cover hit penalty (70%) stack?

Due to the fact that 0.7*0.7 is 0.49 the first student to read this post does not have to show up to class to get a C- if this post is true.

It's the teacher's fault for being silly.

February 6, 2009 | Unregistered Commentermjw

There is a huge ongoing thread about this on Teamliquid.net Sirlin, look specifically on the pages 14-15 for posts directed to you. http://www.teamliquid.net/forum/viewmessage.php?topic_id=86501&currentpage=15

February 6, 2009 | Unregistered CommenterSpoR

specifically Rekrul and CharlieMurphy's posts actually.

February 6, 2009 | Unregistered CommenterSpoR

Reading Rekruls posts would be very educating for you Sirlin, he may be a very blunt person and reading the 'fuck yous' he throws at you may be annoying, but he happens to be the guy with knowledge and not just knowledge but huge loads of inside information and opinions of professional gamers and the fact that he has actually played SC himself on a professional level says a lot as well.

Rekrul isn't the only one who has this kind of view on the case, in fact, I believe you, Sirlin, are the only 'notable' person in the scene still fighting against APM and mechanics. I'm not sure if calling you 'notable' is right actually, I mean, sure you are at fighting games but have you ever played StarCraft on a serious level?

If you can beat the arguments that Rekrul threw at you, then wow, you are a genius.

February 6, 2009 | Unregistered Commenterdsomethingjeja

i've just started to play it now :D
musicisall

February 6, 2009 | Unregistered Commentermusicisall

mjw:

if the two 70%-to-miss penalties stacked, it would only be be 9%-to-hit and 91%-to-miss not 49%.

February 6, 2009 | Unregistered Commenterrealize

It's a 70% chance to HIT when the opponent is behind cover/up a ramp. That's a 30% chance to hit. If the two stack (I don't think they do) it then becomes 49% chance to hit.

Although that's clearly not what the instructor was asking for. The context was the elusive evasion mechanic based on the unit moving.

February 6, 2009 | Unregistered CommenterSeveredevil

"Feng asked, "If your opponent sends wave after wave of Zealots at you, what do you think is next?" One student answered "more Zealots" and I thought to myself that would make a good Rose player in Street Fighter Alpha 2."
Ahahahahahahahah. Beautiful :D

February 6, 2009 | Unregistered CommenterTrumpet

Rekruls is so good at starcraft he doesn't actually have to even READ sirlin's comments to debunk them.

"can someone just link me to all the bullshit he wrote so i can end his life completely? thx"
"hello, can someone please make sure sirlin gets this:"

This is clearly a man whose power level far exceeds the 9000 required to win a debate!

February 6, 2009 | Unregistered CommenterPsymunn

mjw wrote: "Does the High Ground vs Low Ground hit penalty (70%) and the Cover hit penalty (70%) stack?

Due to the fact that 0.7*0.7 is 0.49 the first student to read this post does not have to show up to class to get a C- if this post is true.

It's the teacher's fault for being silly."

Alan Feng is talking about when dragoons completely miss SCVs on flat ground.. no terrain changes or cliffs.

February 6, 2009 | Unregistered CommenterLore

"This is very, very difficult (impractical in a real match to do it to the degree shown in the video)"

You know that, the game he showed is from a proleague. It's very common and not impractical. It's just micro, and any decent player can do that with no problem. It's like doing a simple combo, for you fighting game fans.

February 6, 2009 | Unregistered CommenterIntervigilium

Intervigiluim: I know you like to read through looking for anything you can possibly nit-pick for the sake of it so you can disagree about something, but it would be nice if you posted constructive comments that have an actual point instead.

The video I'm referring to was not a game at all. It was a controlled situation outside of a game that demonstrated Marines completely avoiding Lurker attacks several times. Feng said that at first people thought the video was fake, but it turned out to be real. If you somehow disagree with something there, I'm only the messenger so take it up with Professor Feng.

dsomethingjeja: I can't tell if you're joking or not, but I think you were serious. Rekrul's arguments are a series of fallacies, namely: ad hominem attack, straw man (mostly this one actually), non-sequitur, and one there isn't a fancy name for that I'd call "only a Dune 2 champion is allowed to make any statements about Dune 2." There is nothing really to refute at all because no valid argument was given. Also, you overgeneralization of what I'm talking about shows that you're only trying wave flags rather than really discuss anything, so stop posting things like that.

What a disappointing start to this post's comments. From now on, try commenting on the class itself. If you want to talk about things other than week 2 of the UC Berkeley class, then use the forums.

February 6, 2009 | Registered CommenterSirlin

"The Wraith attacked the Drone. In moments, it would die. Before it did, the Zerg player put the Drone inside an Overlord, just to buy a little bit of time. He then used the Defiler's Dark Swarm many, many times in a row as a way to transport the Drone safely to a gas mine. With swarms everywhere and temporary protection from the Wraith, the Drone mined enough gas to build Scourge, then used the Scourge to kill the Wraith. This made the game a draw instead of a loss."

I really liked this story haha. It's awesome to think of games ending in a draw like this especially when something like 1 additional wraith or 1 muta would completely have caused the game to go one way or the other. It really makes you realize just how valuable each unit is even when you're charging in with a 100 of them.

February 6, 2009 | Unregistered CommenterLogo

Sirlin, it was a vod from Iloveoov. yes, it looks like a fake, but anyone who at least follow the progaming scene knows that.
Besides that, no, I'm not "nit-picking" anything. I liked your post, but I needed to point out that little mistake you made.
And you are the last person who can accuses someone of "ad hominem". Yes, rek was kind of harsh, but you are, too, with that kind of reply(not only to him, but to me or anyone who tries to talk to you about APM).

jeez, chill out.

February 6, 2009 | Unregistered CommenterIntervigilium

by the way, the game you are referring to(the one with the last drone) is known as "trail of tears", is sir@soni vs chunsang. you can see it here: http://www.youtube.com/watch?v=DA_uqz_Juxc @ 1:55

February 6, 2009 | Unregistered CommenterIntervigilium

I don't have anything particularly intelligent to add, but... wow do posts like the linked ones (particularly Rekrul's) make me glad i'm here instead of over there or on some other forum like that...

February 6, 2009 | Unregistered CommenterWinter

Intervigilium: I try to attack the ideas as being wrong, that is not ad hominem. I think your statement that I attack the person rather than the idea is very unfair. In Rekrul's case, I'm pointing out that he's arguing against things I never said, saying things that don't relate to the point, saying that a game designer can't comment about game design basically (only champions of that particular game can make any statement at all?), and several ad homimen attacks as well. I'm not saying anything about him personally, just that those are not actual arguments.

I also don't know what you are saying the mistake is about the video of avoiding the lurkers. No, it really wasn't a match. Yes, it really was a vid of a controlled situation outside of a match. So what is the mistake?

Also, dded "trail of tears" video, thanks for that Intervigilium.

February 6, 2009 | Registered CommenterSirlin
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