Plotwise, you are correct, but:
MGSV was my first Metal Gear game. I found that Ground Zeroes does a terrible job of teaching you how to play, while The Phantom Pain eases you in gradually. I had to play 10-12 hours into TPP before I understood well enough to finish GZ.
Yeah, GZ kind of throws you in the deep end. The only safe space they give you to experiment is the cliff at the start, and even then there's a chance that the first watchtower will spot you with its searchlight.
For those thinking about diving in, here are some helpful tips:
+ When sneaking around, you might notice a white marker onscreen. This indicates an enemy is
starting to notice you. It also indicates the direction from which they're starting to notice you. Don't panic — just keep moving in the opposite direction while keeping a low profile (crawling or crouch-walking). That way, the enemy will either chalk up what he saw to his imagination, or if he begins to walk over, you'll no longer be there. Unless the enemy is right next to you, it'll generally take a while for the enemy to realize what they're seeing, so don't worry about the marker... Just lie low or keep moving.
+ The following variables affect how easily enemies can spot you: 1) proximity — how close you are to the enemy; 2) stance — whether you're crawling, crouching, or standing; 3) movement speed — whether you're tip-toeing, walking, jogging or sprinting; 4) camouflage — whether you're blending in with the environment, i.e. bushes; 5) cover — whether you're behind something or under something that will obstruct the enemy's view; and 6) light and shadow — with dark areas making it easier to stay hidden (try turning off searchlights and shooting out lights with a suppressor-equipped weapon).
Weather also plays a role. Sandstorms limit the enemy's vision and hearing, but they also limits yours. Rain muffles the sound of footsteps. Fog reduces visibility. Cloudy weather also reduces visibility, but to a lesser degree.
Generally speaking, if any enemy is within 10-20 paces of you and facing your direction, stick to crawling. If they're farther away or their back is turned, feel free to crouch-walk at full speed. This is perfect for ambushes...
+ Sneak up behind enemies and hold R2 to restrain them. Then you can interrogate them, kill them, or put them to sleep with a chokehold (throttling R2 repeatedly). You can also knock out enemies from afar with your tranquilizer — and if your suppressor hasn't worn out, you can do so silently. You'll then want to pick up the bodies and move them out of sight by dropping them in the underbrush, behind cover or in a shadowy corner.
+ If you're spotted, you'll go into Reflex Mode, where time slows down for a few seconds so you can neutralize the enemy before they trigger the alarm. Quickly go into first-person view and line up a headshot with your crosshairs. Or if they're within reach, just perform CQC (close quarters combat) by repeatedly tapping R2.
+ If you're spotted by the enemy, run away from where you were spotted (the area the guards will search most thoroughly) and hide somewhere until the enemies drop the alert and call off the search.
+ Try misdirecting enemies: Shoot the wall behind them to make them turn around; plant C4 explosives (found in the shed guarded by the searchlight in GZ) on one end of a base, and then detonate them to draw guards away from your location; and so on.