[G] PvP 1 Gate Robo FE

9 Pylon
Chronoboost 11th Probe
12 Gate -> scout
Chronoboost 13th Probe
14 Gas
Queue up 3 more Probes (17)
17 Cybernetics core
17 Pylon
18 Gas
18 Gas steal (if possible)
22 Stalker Chronoboosted
(cut probes)
22 Pylon
24 Stalker Chronoboosted
24 Robotics Facility (once scouting Probe is gone)
26 Stalker Chronoboosted.
Build two more Probes

Will stop using supply as indicators here as it becomes too variable

Push out with your 3 Stalkers, this is to prevent/delay any possible 4 gate, during this time you should be building 2 Sentries (Chronoboost it out) and an Observer, cutting Probes again get your expansion down, (if they are 4gating, don't expand, put down 2 more Gates and defend like normal with Sentries and Immortals) Warp gate should be finished once the 2nd Sentry is done, warp in another Sentry and begin your first Immortal asap, build 2 more Gates asap and continue Sentry production until you have 5 and continue Immortal Production until you have 3-5 depending on your opponents build.
Build your tech accordingly to what your opponent is doing, the match up is still a coin flip build order fight, you get a very early Observer so you can tech in the right direction.
(Continued Immortal production with Blink versus Blink openings, Stargate versus Robotics tech, Gateways versus Stargate)

The 3 Stalker pressure must be executed very effectively, you must either return with all 3 Stalkers unharmed, or do damage to their starting units/forcing out Sentries to delay their tech, if you lose your 3 Stalkers by overextending at their ramp and getting Forcefielded in, you will be very vulnerable to any Stargate tech, you money is very limited while building up the initial defence units (Sentries and Immortals) that it is very hard to (without cutting Probes) to replenish these Stalkers.

This build is not secure against a 4gate, if your opponent is 4gating you cannot expand until it is held off, as you build Sentries and Immortals early on, it is very easy to hold.

This build does involve cutting Probes, points to cut Probes have been said however as the game is so endlessly variable you will find sometimes you can keep building and sometimes not so it comes with practice of the build to know when it is best to cut Probes, remember you're expanding much earlier than your opponent normally will so cutting Probes will not put you behind for very long.

Good forcefields is essential to pull this off.

A gas steal is very useful however not totally needed, the gas steal prevents fast Colossi with range timings, DTs (as you only have one Observer) and delays other tech (especially with the 3 Stalker pressure, if you do it well enough to also force them to build Sentries you can delay their tech even further)

The biggest factor of this build is how it is basically inducing them to attack you, in PvP when you scout a finished expansion and you have not even started your own, the general mindset of most players even in high Masters (cannot say for higher) is to attack instantly, this works in favour of this build due to the high Sentry and Immortal count, with good Forcefields you tear apart any Gateway army.

The build transitions nicely into Colossi tech due to possible 4 gas and already Robotics tech.
The build transitions nicely into air tech due to already having ground dominance with Immortals, making it much harder for Stalkers to be an effective counter to your air play from the opponent.
The build transitions nicely into Chargelot Archon tech due to high Sentry counts allowing you to prevent them kiteing Zealots, or squeezing them all together for an Archon hit.

If a 4gate is coming you can very easily hold it before expanding due to Sentries and Immortals.

When pulled off you're an expand ahead of your opponent.

Due to a fast Observer you have good scouting from the start and can prepare very early on against any potential push.

Due to the Immortal buff, Colossi pushes without range can be held fairly well.

If you manage to do the gas steal, this is still enough to prompt a lot of players to fall back on the 4gate, which in current game standings is a free win for you.

Due to being very immobile because of Immortals and Sentries, this leaves you very vulnerable to Phoenix play done correctly (by correctly I mean the harass and kill the Sentries ((however this could be because Phoenix's in PvP being the rarest build I face, I may just not of had the experience to react accordingly and the build may be fine against it))

Colossi with range timing pushes can be hard to hold, however more testing may be required to say this 100%

A very fast gas steal from your opponent can slow this build down due to lack of Sentries, plus it delays the 3 Stalker pressure which is essential.

Due to immobility Warp Prisms with speed (the double Immortal drop or just Zealots) can cause a lot of damage if you do not catch it before it does damage.

This build relies on your opponent directly engaging, or just expanding themselves, if they go for harassment in the form of Warp Prisms or Phoenix's without engaging your army, they will be able to hit a timing where your Sentries are either killed by Phoenix's or your Forcefields will not be in a position to help you (such as 4 gate Warp Prism special tactics style.)

Versus 4gate;
As with any opening in PvP they must be able to defend 4gates, here are 2 replays of how you would react to a 4gate.
http://www.sc2replayed.com/replay-videos/13860
http://www.sc2replayed.com/replay-videos/13861

Versus Blink Stalker opening;
http://www.sc2replayed.com/replay-videos/13862

Versus Blink Stalker all in;
http://www.sc2replayed.com/replay-videos/14532

Versus 4 Gate Robo Immortal pushes;
http://www.sc2replayed.com/replay-videos/13865

Versus Expand into Colossi;
http://www.sc2replayed.com/replay-videos/13866

Versus Stargate Phoenix;
http://www.sc2replayed.com/replay-videos/13867

Versus Colossi with range timing;
http://www.sc2replayed.com/replay-videos/13875