Part 01 - Prologue

For the record this has to be one of the best opening chapters I've seen in any game for good while. Had to actually pause and stare at the screen for a minute just to absorb everything when it ended.

Anyway, the chapter starts with 9S working to weaken the enemy's air defenses. Here you have to hack into four different machines without destroying them. If you do accidentally destroy one however, just wait on that particular target location until a replacement appears. The fourth target at the commercial facility is a giant biped that can only be hacked while controlling another machine lifeform. Take over one of the small frys nearby first then try to hack the big one. Head for the bridge leading to the Abandoned Factory afterward. By the way, if you managed to completely disable the enemy's air defenses, Operator 21O will leave a reward for 9S in her room at the Bunker. You can go get it before joining up with 2B.

Controls will now switch over to 2B. Your objective this time is to assist other attack squadrons and take out all the enemies in each target area. Defeating the last group of hostiles will set off an EMP blast and force 2B to reboot. Provide cover as 9S until the process completes. These enemies can cause all sorts of problems when you're caught by their EMP blast so hopefully you have plenty of curatives on hand to remove some of the abnormalities.

Just when everything seems well again, the logic virus strikes and cripples every YoRHa unit, 2B included. You can hack into other YoRHa units to try and save them but it won't really matter in the end so just help 2B. The virus drives everyone else insane soon after but you won't be able to attack them until 9S disables 2B's identification signal. With that done, take out as many targets as you can (they drop loads of enhancement items) until you receive a marker to the enemy responsible for jamming your comms.

Go destroy it. And when efforts to reach command continues to fail, 9S comes up with a plan you'll have to cover him until he completes the data upload. Once you're back at the Bunker, go speak to the commander and things go from bad to worse. Defeat all the infected YoRHa units until 9S gets the elevator working again. This is a good opportunity to farm extra enhancement and recovery items if you use them often. Equip high level drop rate chips to get more. You will also get an extra dialogue from Operator 6O here thanking 2B for the flowers if you completed the Find a Present sidequest. Fight your way through the dormitories toward the hangar where 2B and 9S escape.

Upon reaching earth however, they are ambushed by YoRHa units and 2B's flight unit ultimately crashes at the Flooded City. The virus infection does not start until you head to the direction of the sewers so you can stay and defeat the hostiles if you want. Once the virus takes hold, you will want to find the shortest and simplest possible route to the commercial facility before the system corruption reduces your screen to a garbled mess. Equip Moving Speed chips to make 2B move faster.

Once you you make it out of the sewers, turn right and keep going forward until you see an upward slope beside you. Take that and jump across the gap before turning toward the city proper. It should be a straight shot from here, and all you need to do is find the bridge that connects to the commercial facility. I've also noticed that the developers may have implemented a "safety net" feature during this part of the game. Because while you can still save, the game does not actually record any of your progress (except total playtime) beyond the Flooded City. At least until 2B's virus contamination segment is completed. Most likely to prevent players from getting stuck at a point of no return.

I say this because I had foolishly overwritten my one and only save file during this time, after being cornered by enemies and falling all the way down to the cave area. The virus had advanced far enough to make traversal difficult so I'm essentially stuck. By now I was quite sure I'm totally screwed but was very relieved to find that my last data was at the Flooded City despite having saved only seconds before. Still it's best to avoid saving until you've made it passed this point of the game just in case.

Anyway, when control shifts over to 9S go to where to 2B is to witness the final scene that concludes this chapter.