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[G] Walling Mechanics

Forum Index > StarCraft 2 Strategy
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Orek
Profile Joined February 2012
1665 Posts
Last Edited: 2013-03-07 06:37:23
December 26 2012 23:09 GMT
#1
[G] Walling Mechanics

[image loading]

Wall not tight enough

Introduction
According to liquipedia, “walling” refers to the use of buildings in order to make a choke more narrow or even completely blocked off in some situations. After more than 2 years since the release, we often take walling sim city for granted today. Any decent player knows how to wall in any match-up without giving much thought to it. However, most of the time when we construct a wall, we rely on our experience rather than precise knowledge of walling mechanics. I have always felt that we, including pros, don’t understand the walling mechanics in SC2 as clearly as we should. Therefore, while it is impossible to explain every single walling situation on every single map, this thread attempts to explain universal walling mechanics at a very fundamental level. HotS will change the metagame significantly in all 6 match-ups, but this walling mechanics doesn’t change. So, this must be a helpful read for those who are already playing HotS beta, too.

Walling Components
+ Show Spoiler +

Roughly speaking, there are 2 kinds of walls:
1. wall between a building and a map feature such as ramp/cliff/doodad/edge etc.
2. wall between a building and another building
This thread is all about the latter, and the former isn’t discussed. This is because ramps/cliffs/doodads/edges are fairly map-dependent so that one example at a particular place on a particular map doesn’t apply to other cases, which makes drawing meaningful conclusions impossible. On the other hand, the relationship between a building and another building is completely map-independent so that test results are consistent. For example, in the image below, it doesn’t help much outside of this particular ramp on Entombed Valley to know that A and E are tight walls because this exact shape of ramp/cliff doesn’t appear anywhere else. Instead, it is more meaningful to note that B and D are tight walls and C is what I later call semi-wall because the only factor in question in these cases is the relative positions of two adjacent buildings regardless of the map (or race for the matter) played.
[image loading]


Relative Position (prerequisite)
+ Show Spoiler +

Most buildings can be categorized into 4 groups by their sizes: 2x2 (spine/spore), 2x2 (normal), 3x3 and 5x5.
2x2 (spine/spore) includes only spine/spore crawlers. To distinguish from 2x2 (normal), this size is defined as SxS in this thread. SxS is slightly smaller than 2x2.
2x2 (normal) includes all the other 2x2 buildings. 2x2 refers to this size from here on.
3x3 includes all 3x3 buildings except for refinery/extractor/assimilator.
5x5 includes CC/hatchery/nexus and their variants.
Sensor tower and creep tumor are hardly ever used as a part of a wall, so 1x1 is not relevant enough here.

There are 10 combinations in choosing 2 buildings for a wall:
SxS and SxS [S-S]
SxS and 2x2 [S-2]
SxS and 3x3 [S-3]
SxS and 5x5 [S-5]
2x2 and 2x2 [2-2]
2x2 and 3x3 [2-3]
2x2 and 5x5 [2-5]
3x3 and 3x3 [3-3]
3x3 and 5x5 [3-5]
5x5 and 5x5 [5-5]

Because buildings use symmetric footprints, test results in 0-45 degrees account for the entire 360 degrees. Therefore, for the sake of easier notation, bottom left corner of the smaller building of the two is taken as the origin, then x-y coordinate of bottom left corner of the other bigger building is defined as the relative position these two buildings have.
[image loading]

[image loading]

By reflection and rotation, any relative positions in 45-360 degrees ultimately end up with one in 0-45, so it doesn’t matter bottom left corner seems to be somehow more favored, if you will, than the other corners.
[image loading]

[image loading]

[image loading]

This notation system allows us to clearly denote all relative positions. I hope it makes enough sense. I wish I knew a better way to explain this concept.


Type of Wall (prerequisite)
+ Show Spoiler +

There are primarily 5 different types of walls. 7 if minor differences in rare cases are taken into account.
[image loading]

Loose wall Lv.0 is not walled at all. All units can pass between 2 buildings that form loose wall Lv.0.

Loose wall Lv.1 blocks only 2 units:
Terran: thor, (siege tank)
Siege tank is blocked even with loose wall Lv.0.5 which is seen very rarely.

Loose wall Lv.2 blocks additional 2 units:
Zerg: ultralisk
Protoss: archon

Semi-wall (or loose wall Lv.3 in a sense) is the most important type of wall at least here in this thread. Just like semipermeable membrane for osmosis in chemistry, semi-walls block big units but allow small units to pass. This selective feature is very useful in some situations. Of course, loose wall Lv.0.5~2.5 work in a similar way, but they block too few units to be useful compared to semi-walls. Additional units blocked by semi-wall:
Terran: hellion
Zerg: queen, roach, infestor
Protoss: stalker, immortal, (colossus)
Colossus is blocked by rare loose wall Lv.2.5 as well.

Tight wall (or you could call it loose wall Lv.4) doesn’t allow any unit to pass between 2 buildings. We usually call this type “wall” and everything else is not wall per se. Most of the time, this tight wall is what we want to make with 2 buildings. These small units are finally blocked with tight wall:
Terran: SCV, mule, marine, marauder, reaper, ghost, viking (assault mode)
Zerg: drone, zergling, baneling, hydralisk, broodling, changeling, infested terran
Protoss: probe, zealot, sentry, dark templar, high templar

Colors are chosen for their role similarity to the corresponding traffic light color. Green - sea green - light green have relatively small differences among themselves.


Research Results (main)
+ Show Spoiler +

Enough with prerequisites. What we want to know is, “Which relative position has which type of wall?”

[S-S]
+ Show Spoiler +

[image loading]
* loose wall Lv.0.5
** loose wall Lv.2.5

[S-2]
+ Show Spoiler +

[image loading]
Two buildings can never occupy the same grid. (X on the left side) Two buildings are 2 grids away horizontally = loose wall Lv.0 regardless of vertical coordinate and building sizes. (empty graphs on the right side) For these reasons, only the relevant middle part will be shown for the rest of images below.

[S-3]
+ Show Spoiler +

[image loading]

[S-5]
+ Show Spoiler +

[image loading]

[2-2]
+ Show Spoiler +

[image loading]

[2-3]
+ Show Spoiler +

[image loading]

[2-5]
+ Show Spoiler +

[image loading]

[3-3]
+ Show Spoiler +

[image loading]

[3-5]
+ Show Spoiler +

[image loading]

[5-5]
+ Show Spoiler +

[image loading]

ALL
+ Show Spoiler +

[image loading]

ALL (simplified)
+ Show Spoiler +

[image loading]



Semi-wall
+ Show Spoiler +

[image loading]

Never use these 7 relative positions when you want a tight wall. Some of them might be counterintuitive, but workers, zergling, zealot etc. will laugh at the wall and run by between these 2 buildings. I don’t often see a pro fail with these semi-walls because they already know from their experience that a tight wall has to look tighter, but I’m sure some of the ordinary players here have failed miserably before… at least, I have T_T. For example, when you CC first at ramp in TvZ, make sure the wall doesn’t include [2-5 (2,1)] or [3-5 (3,2)] so that you can hold an early pool. Or, when you FFE in PvZ, make sure your forge and gateway don’t look like [3-3 (3,3)]. Green loose walls look wide open rather obviously, but these yellow semi-walls sometimes look deceivingly tight enough, so be careful.


vs Hellion
+ Show Spoiler +

Semi-walls are not always bad. There are some practical applications especially against hellions. As explained in “Type of Wall” section, a semi-wall blocks hellions while it allows passage of workers/zergling/marine/marauder etc. Some sim city can take advantage of this fact.

TvT
+ Show Spoiler +

[image loading]
No hellion run-bys with [2-2 (2,2)] semi-wall, yet it doesn’t hinder your move out or rally point. When you go bio vs meching opponent, your SCVs would be thankful if you use this simple sim city to save them from potential massacre by hellions. I watched a pro game where this wall-in was used a few months ago, so I guess this is nothing new for some people.

ZvT
+ Show Spoiler +

[image loading]
[image loading]
[3-3 (3,3)] blocks hellions while your drone/zergling/baneling can still move out. This wall-in doesn’t require queens to fill the gap. In fact, queen/roach etc. can’t get out without moving the spine crawler. Generally speaking, using units to complete a wall has a risk that the unit ever so slightly off the center mark could fail to block run-bys. In this regard, unit-free wall-ins are safer and more reliable.

PvT
+ Show Spoiler +

[image loading]
[image loading]
Damage from hellion drop strategy can probably be reduced significantly by forcing hellions to take much longer route to catch up with running probes. A semi-wall near nexus secures an escape route for those vulnerable probes and buys enough time for your units to arrive. I haven’t seen this tactic used by anyone, nor have I tried it myself on ladder, but it should be viable in theory. The only thing you have to keep in mind is that mineral-walking probes is a must with this sim city; otherwise, probe traffic jam at choke point actually benefits Terran player. By the time hellions arrive, you should have many more buildings in your base than the images above, so hellion paths can be blocked even further with careful sim city.



Final Thoughts
+ Show Spoiler +

Ever since I posted [G] Zerg Sim City for Spire protection in ZvP 4 months ago, I have always wanted to do a comprehensive research on walling mechanics that explains “incomplete wall-in hole examples” in that thread. I am easily distracted and have written several other articles/guides, but finally here it is. With a bit of compromise in quality, I managed to publish this research before 2013. When I started this research, I was hoping to find more practical applications than just presenting facts and data. Also, it would have been nice if I could include analysis on units filling the gap between 2 buildings. (hold position zealot, queen etc.) Well, I guess the content is in-depth enough as it is, nevertheless. As far as I know, the only difference in HotS is that spine crawler is bigger than that of WoL (same size as other 2x2(?)) There might come other changes in future, but majority of basic walling mechanics explained in this thread must remain relevant enough even after LotV. If I find time and passion again, I might follow up with HotS and LotV versions of walling mechanics. As always, thank you for reading. Any feedback is much appreciated.


Orek's Articles/Guides
+ Show Spoiler +

+ Show Spoiler [Article etc.] +

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A bit on BitByBit
IlIlIlIlIlIl or lIlIlIlIlIlI?
Optimal Creep Spread in Theory
Various Businesses in Starcraft 2
Balance Discussion Math(Best of N format analysis)
Underground Activities in Starcraft 2
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Map Size History & Analysis
Larva disappearing Glitch in 1.5 (not about 20th larva)


+ Show Spoiler [Guide] +

[G] Walling Mechanics
[G] Unit/Structure Selection Priority
[G] ~8% faster gas mining
[G] ZvT Perfect Spine placement vs 2rax Bunker
[G] Zerg Sim City for Spire protection in ZvP
[G]Health Bar Color
[G]Map Distance & Travel Time

LiLSighKoh
Profile Blog Joined October 2010
United States588 Posts
December 26 2012 23:22 GMT
#2
Nice walling guide! I myself have problems like on Ohana where I bunker up the ramp back enough to where i can put depots in front... I always mess up the middle one.
"Want some? Go get some!"
`dunedain
Profile Blog Joined April 2011
655 Posts
December 26 2012 23:32 GMT
#3
Awesome stuff! Need to link this to a couple friends who still wall off like shit.
"In order to be created, a work of art must first make use of the dark forces of the soul." ~Albert Camus
AGcomandyzo(toss)
Profile Joined March 2012
United States1 Post
December 26 2012 23:45 GMT
#4
good information but unless im reading it wrong it seems the hellion wall offs will hurt you most of the time. it will slow down the hellions entering your base but if you ever want to leave your base it lines all of your units and makes light units evaporate especially zerglings and probes
SomeONEx
Profile Joined April 2011
Sweden641 Posts
December 27 2012 00:27 GMT
#5
Great research!
BW hwaiting!
Surili
Profile Blog Joined March 2011
United Kingdom1141 Posts
Last Edited: 2013-01-01 23:47:47
December 27 2012 00:44 GMT
#6
Thanks for the guide, love the stuff on building hexes in this one and other guides, i still always get my probes stuck against my nexus though ^^

[image loading]
(Completely zergling proof)

A 1.5 hex is enough for an archon to walk through, it doesn't have to be a full 2 hex. hence a diagonal pylon-gate wall is enough,

On top of that, for defending mutas it means the opening is in the middle, meaning units do not have to run all the way around to defend mutas/roach drops etc.
The world is ending what should we do about it?
porygon361
Profile Joined August 2012
81 Posts
December 27 2012 01:10 GMT
#7
Once again, another great thread by you once again, Orek!

So what's your next guide gonna be about?
"Sometimes life is like this dark tunnel. You can't always see the light at the end of the tunnel. But if you just keep moving, you will come to a better place."
mau5mat
Profile Blog Joined September 2012
Northern Ireland461 Posts
December 27 2012 01:30 GMT
#8
Fantastic thread, good work!
Atrbyg
Profile Blog Joined October 2011
United States513 Posts
December 27 2012 01:52 GMT
#9
Thanks for the thread. I've been trying to incorporate walling off into my games more after seeing Flash use it to great effect in the proleague.
darkrage14
Profile Joined May 2010
Canada173 Posts
December 27 2012 02:07 GMT
#10
Orek, you are awesome.
Sjokola
Profile Joined November 2010
Netherlands800 Posts
December 27 2012 02:08 GMT
#11
You always deliver good work!
Hope this becomes metagame (just as walling in spire, don't understand why people don't do it)
Host-
Profile Joined December 2010
New Zealand459 Posts
December 27 2012 03:04 GMT
#12
wow those zerg walls are epic. Definitely going to go and play around with these now!
Najda
Profile Joined June 2010
United States3765 Posts
December 27 2012 16:13 GMT
#13
Wow those semi-walls are very usefull. I'm definately going to start including those more in my play.. just gotta remember em now.
Targe
Profile Blog Joined February 2012
United Kingdom14103 Posts
December 27 2012 19:24 GMT
#14
Wow, always so impressed when people come out with these threads.
The 2x2 depot wall looks incredible, I would never have thought of that vs. a meching player.
11/5/14 CATACLYSM | The South West's worst Falco main
HexSCII
Profile Blog Joined October 2011
Canada115 Posts
December 29 2012 17:14 GMT
#15
Thanks for this, it is really helpful!
Nexus first or die trying. partinG/MC/oz/Squirtle/Nani/ HerO
Hollandrock
Profile Joined January 2012
United Kingdom158 Posts
December 29 2012 17:53 GMT
#16
This thread... Is amazing...

Hadn't ever thought about the possibility of blocking hellion run bys while still allowing marines through the gaps... Much better lowering the depos etc... thanks!
Syrinks
Profile Joined December 2012
France14 Posts
January 15 2013 14:54 GMT
#17
I must say the 2x2 depot wall works to great effect versus a meching Terran.

Last TvT on ladder, on antiga, i 2x2 walled my third (bottom right spawn) and it did wonders!
I am not sure if the 2x2 wall is doable on every third. Actually, an extensive list of locations of maps this wall is doable on would be amazing!
y0su
Profile Blog Joined September 2011
Finland7871 Posts
January 15 2013 15:30 GMT
#18
It's funny I was just thinking of this relative to being able to do a high ramp wall while going CC first - preferably using only CC and Rax [3-5].

You can achieve a full wall with only those two buildings on Entombed valley and Cloud Kingdom. (Main reason I like to do this on Entombed is that an early scout wouldn't see the supply depot and might skip to another location without fully scouting my location - a little less unlikely with the spawn position update.)

AFKing
Profile Joined January 2013
128 Posts
January 15 2013 15:40 GMT
#19
I honestly didn't think there was this much to walling off, great guide.
THM
Profile Joined November 2010
Bulgaria1131 Posts
February 01 2013 10:59 GMT
#20
Great post, Stephano could've used that semi wall against Bogus in GSL today
1 2 Next All
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