1) One gateway and one forge block the entrance.
2) There is exactly one spot zerglings can pass through.
3) That spot is 1-matrix wide to allow passage of dragoons.
4) Pylon placement leaves rom for cannons so that both forge and gateway are in range.
Now, if the wall-in meets all the requirements listed above, a protoss will generally have a MUCH easier time vs whatever zergling attacks that might happen. In fact, when the gap is blocked by zealots not probes, a zergling all-in is pretty much totally ineffective.
Important notice #1: on many maps perfect wall-ins are impossible. So post those that you find best for the given map and the given location.
Important notice #2: these wall-ins are optimized vs zergling aggression. They are NOT the best ones vs hydra as most of them leave your forge exposed to hydra fire just due to their nature.
Important notice #3: They are surely not the only way to block your choke. Experiment is the king of all sciences.
EDIT: As more general wall-in rules:
- Forge below gateway is impassable.
- Usually gateway below obstacle is passable despite looking very tight
- Forge below obstacles is usually impassable.
- Gateway above obstacle is usually impassable, but make sure you don't trap your zealots like in that famous game when some protoss went 2 gate proxy and trapped his initial zealots, so he gg'd before even being scouted.
- Gateway to the left of an obstacle is often impassable.
- Forge to the right of an obstacle is oten impassable.
- Forge is generally more likely to block than gateway.
- Pylons don't block anything except minerals.
- Minerals have 100% collision size (2 matrices), therefore, they block with nearly anything.
So, I'll start with Tau Cross and Longinus (EDIT: I will actually update the OP with all maps done here):
+ Show Spoiler [Longinus] +
+ Show Spoiler [Tau Cross] +
Kudos for the last two goes to ZerG~LegenD
+ Show Spoiler [Blue Storm] +
+ Show Spoiler [Python] +
Kudos to ZerG~LegenD and humblegar
+ Show Spoiler [Luna] +
Note that at this moment I've only seen one wall-in that I've found satisfactory. Depending on further feedback the wall-ins that didn't get here now might get through if noone finds better.
Kudos to ZerG~LegenD
+ Show Spoiler [Shin Peaks of Baek-Du] +
Kudos to humblegar
"That should be all for now. Not that this took me a great effort to do, but after watching the WGT reppack I was downright amazed at how many tosses die to zerglings due to poor building placement. I urge everyone who has wall-ins for other maps memorized to post their screenies."
EDIT: OP massively updated. This will now be kept more or less up to date. Note that the OP will only contain one wall-in for each position, usually it will be the best one posted up to date^^