This is not a walkthrough. This is a checklist of things that can be missed in each area. Although nothing in the game is permanently missable (with the one exception of ending Y), the chapter select for replaying any part of the game unlocks only after you fully complete the main story. This checklist is for getting as much as possible done during the main story.
Directions: This checklist uses two kinds of directions — absolute (north, south, east, west, etc.) and relative (left, right, up, down). Follow absolute directions using the minimap with rotation switched off; the relative ones are for areas with fixed side-scrolling or top-down camera.
: Extra information — a tip, advice, recommendation.
: Explanation of exact location of the item/quest/etc.
: Warning about a potentially missable or otherwise failable.
: Quests and their conditions, at the point where you can start them.
: Instances where it's possible to repeatedly acquire an otherwise rare material or item.
: An enemy to be talked to (if friendly) or defeated for a Unit Data entry. You will acquire most (~90%) unit data automatically by completing all other objectives (finding all chests, quests, etc.), the checklist includes the remaining — those more out of the way and/or only appearing in cleared areas in later routes.
: A piece of Old World data.
: An optional boss fight.
: A weapon.
: An extra pod, pod program or limited availability upgrade material.
Routes and endings
Routes: When you play the game for the first time, that's route A. After you finish the game, you can continue from the same file and start again, this time with a different character — that's route B. Continuing after route B will bring you to route C, the third and last part of the main game.
Persistence: All fully completed side-quests and open chests remain so permanently across all future playthroughs (including chapter select); the only exception to this is Abandoned Factory (not including Underground), where the chests are reset when first starting a new route. You also retain your character progression: items, chips, weapons, pods, level etc. Things related to main story quests, incomplete quests and any shortcuts you've opened, all get reset between routes A and B. The only exception is Half-Wit Inventor, who always retains the invested amount.
Route-common: The majority of quests and chests can be accessed by during either route A or B (but not route C!). These have no special label in the checklist.
Route-specific: Things specific to a route are labeled using
route-c— these can only be accessed in the route(s) labeled.
Character-specific: Things available to a specific character (regardless of route, unless otherwise specified) have the corresponding label(s) —
Endings: There are 5 "main" endings (A through E), which incrementally tell you the game's story and which you get by playing the game. Getting ending C or D depends on who you choose during the final moments of route C; however, chapter select unlocks right afterwards, allowing you to replay any part in any route. This lets you go back and choose the other character for the other ending. Once you've gotten both C and D endings, you will have to play a minigame during end credits that, when won, will unlock ending E.
The other endings (F through Z) are "joke" endings that you can get by performing specific actions in the game (most often — failing time-sensitive tasks or abandoning the action during important moments). All of them do end the game, so you will lose any unsaved progress. Ending Y is the only one that's permanently missable, but it only becomes available once you've collected and upgraded every weapon in the game to maximum level. See Emil's Determination quest in City Ruins.
Getting around: You can speed up your travel by riding animals, by using Animal Bait or having Choice Sachet in your inventory. As you progress through the main story, fast travel will also unlock between access points. Most side quests become available not long before that, so it's efficient to postpone doing them until then.
Inteface: You can scroll lists by pages using
leftdirection buttons. If you double-tap and hold the
cancelkey/button, it will skip through most dialogs quckly.
Shops: Check shops in all new areas you discover. Different areas have different items for sale, and new items are sometimes added after major story events.
Evade distance: You can hold down the
evadebutton to glide further than just by tapping it. This can be further extended with Evade Range Up chips.
Long jumps: You can massively extend your jump distance by combining all the aerial moves in the game. You can double jump, have your pod throw you (
jumpbuttons) and evade while in the air, and light attacks also keep you in the air and move you forward for a bit. Finally there's the glide (hold
jumpbutton while in the air) for landing slowly while still moving in a chosen direction.
Hacking: Lock-on works in hacking, even if there is no visual indicator.
Chips, weapons and combat
Buying vs. finding: All chips sold in shops take up the maximum possible number of slots for their level. For example: a +1 chip can take up as little as 5 or as many as 12 slots, but a store-bought chip will always take up 12 slots.
Chip efficiency: While for most chips +8 is the most efficient way to get the maximum effect, there are a few exceptions where combining multiple low level chips can get the same effect easier and/or using less space (assuming lowest chip cost). See reference for specifics.
Fish for $: If you need money, especially early in the game, do some fishing and sell what you catch. Most fish can be sold for couple thousand $ each.
What to sell: You can safely sell any item whos description says "can be exchanged for money".
How: You can fish at nearly any body of water, either standing in it or next to it, on a bridge, etc. Hold down the
actionbutton to start, and then use the
jumpbutton to throw your pod into the water. Whenever it goes fully under the water, or if it starts moving against the current (if there is a current), press the
jumpbutton again to reel it in. In some spots there is no current, in which case you just have to reel the pod in if it hasn't dipped in a while and hope it has caught something.
Rarity: Rare and very rare fish can be ridiculously hard to get. Catching a very rare fish can take hours and there is no way to increase the odds of getting any one specific fish.
What to catch: This guide doesn't contain every fish in the game, instead, fishing checklist groups less common fish by areas where they are more likely to be caught than in others. By the time you catch each of these fish in the areas indicated, it's virtually guaranteed that you will also have caught every other (more common) fish in the game. The information on fishing comes from the fishing section of PuppyLand's Nier: Automata guide at GameFAQs.