This is not a complete walkthrough. Instead, its a way to quickly get your character to the point when content unlocked by passive skill checks won't be missed. Passive skill checks don't allow you to spend effort, but instead require to be trained (or spezialized) for the extra content to show.
For example, without enough perception, you may simply not notice something. Same for unlocking (some) memories with Anamnesis, or insights from the Lore skills.

In Sagus Cliffs, being trained seems to be enough - in later parts of the game, you want to get skills to level 2 for max content, esp. Perception and the Lore skills and Perception have plenty of passive unlocks.
There are also some oddities that have specialized+ lore requirements to unlock their full description, but this doesn't happen in conversations/envionmental so an artifact can be used to meet that requirement.

Please note that this is about passive unlocks - getting your skills to specialized+ and specialized++ still makes active skill use easier & more likely to succeed.


Passive skill check overview

Not all passive skills are equal in terms of frequency. In order to choose which to pick later, here is a frequency analysis from data crawling the conversations (credit to PointwiseConvergence on r/Torment on reddit)

Perception: 102 Trained, 15 Specialized, 4 Specialzied+ (the only skill with specialized+)
Anamnesis: 38 Trained, 4 Specialzied
Lore Mystical: 33 Trained, 9 Specialized
Lore Natural: 30 Trained, 7 Specialized
Lore Machinery: 21 Trained, 7 Specialized
Tidal Affinity: 16 Trained, 6 Specialized
Persuasion: 4 Trained, 1 Specialized
Healing: 4 Trained
Intimidation: 2 Trained, 1 Specialized
Deception: 1 Trained, 1 Specialized
Melee Weapons: 1 Trained, 1 Specialized
Quick Fingers: 1 Trained

Of course, there are a lot more active skill checks for all skills, this frequency overview is ONLY for passive unlocks.

~~ Falling Down ~~

Read and answer the scenarios however you want, but choose your character yourself afterwards

Type: Nano
Pools: Intellect and Speed are needed most, but Int is easier to raise in game
Abilities: Scan Thoughts, Resourceful
Exploration Skill: Lore Mystical
Descriptor: Stealthy (+1 Stealth, +1 Deception, +1 Ligth Weapons, -1 Initiative, -1 Running)

Why Nano? Only type with Scan Thoughts ability from the start - this ability is used all the time, probably the biggest single unlock.

Abilities: Scan Thoughts due to its amazing unlocks, but Resoureful to delay cypher sickness / keep multiple good cyphers on hands

Descriptor:
We look for descriptors that increase skills which are difficult to increase via Artifacts, cyphers, conversations etc. Good Penalties are
stat points (get plenty in game) or skills that are not/very rarely used outside combat (Endurance, Running, Initiative).
Lore Skills, Perception and concentration are easy enough to push to specialized without Descriptors for a Nano.
So best Descriptors imo are Charming, Slick and Stealthy. Charming has 2 social skills (Perception+Deception) with no downside, however
i prefer Stealthy: also Deception, no Persuasion but gains Light Weapons & Stealth - makes using thoes int-based light weapons more worthwile
and helps with early stealth. Loss of initiative and running is ok (less movement doesn't matter for ranged, slower initiative makes fights more interesting)
You can get Charming or Slick just as well for this build.

~~ The Labyrinth ~~

The Spector (ask him everything)

Tutorial Battle

Don't kill the reflections. If you wait for a while, they will survive (feeling drained) - the
escaping monsters will have consequences laster, but those will be interesting.

Before you go, don't forget to pick up a "Shimmering Glass" Cypher on the floor!

~~Broken Dome~~

Talk with Aligern & Callistige
exhaust all options, say you might be the Changing God for some extra silver tide (if you want)
Ask Alighern to take you to the Cult of the Changing God

Environmental Interactions

Mechanical Arm (with sparks)
Lore (Quick Fingers/Machinery) -> use Alighern: Spray Flesh & ~18 Shins

Resonance Chamber:
Take the "Chrystalline Shard" (melee weapon)

Box left: 10 shin, Encephalic Rush, Fleetfoot Moss

Computer: Use Anamnesis for memory, unlock both compartments
then go outside to

~~ Reef of the Fallen Worlds~~
Talk to Alighern

Pickup (next to the hands sculpture): ~23 shin, Fleetfoot Moss, Elutriated Force

Hands: Smashing (Alighern best) for "Eight-fingered Mace", equip on Alighern
(on fail: +1 permanent HP, but i prefer the weapon honestly for early money)

Obelisk:
Use Crystal Shard -> 3 XP, replaced by "Infused Crystalline Shard"

Dont interact with the dancing cones (yet, lacking required skills)

Tar pit
Quick Fingers+Perception (Callistige best) -> "Fresh Vapors" Cypher (regain +10 Int, +1 Int Edge for next 5 checks)
Look for more objects a few times -> 2 XP, Tar River Globe Oddity (worth 105 shin)

Orange structure: cannot open for now

Pickup items north of the sealed orange structure: ~16 shin, Elutriated Force, Encephalic Rush

Go north and meet Quorro & Gang
Talk, then tell him (truth) you are it (silver tide) -> choose to fight (silver)
Kill everyone but Quorro -> he wants to talk -> ask for compensation (2x Spray Flesh, 29 shins)
Let him go (we loose some extra loot, but he has a small role to play later)
100 XP, tiny gold tide
go with Alighern (for now)

Loot:
White Robed guy: "Thick Air Snare" Cypher, 7 shin, Encephalic Rush, Buzzer (light ranged)
Thief: 6 shin, "Bounder" Cypher, "Image Blocker" Cypher, Fleetfoot Moss, Dagger (light melee)
Golden armor: 3 shin, Walur Oddity, Elutriated Force, Greatsword (heavy melee)

~~Circus Minor~~

we ignore most things for now, and go to specific places to get some items we need.

Companion: Talk to Tybir (standing in the crow) and agree to help -> new companion

Interaction with rockslide in NW corner (behind a character called "The Genocide")
a1: (mutex a2, a3) Quick fingers & lore: machinery -> random # of shins (i had 47, 55)
a2: (mutex a1,a3) Rocks in canister: gold button -> tiny blue tide, Cypher "Conflict Advisor" (89 shin, +30% evasion, +45 attacks for 1 crisis)
a3: (mutex a1, a2) Rocks in canister: aqua button -> tiniy blue tide, Cypher "Shade of the Desert Sun" (60 shin, +7 resistance for 1 crisis)
b1: fail to smash rocks (STR): Cypher "Predistigator", use for +1 training Quick Fingers (!!!)
b2: succeed to smash rocks (STR): shins
Recommend a2 and b1 (certainly b1: Prestitigator for Quick Fingers training is better than shins)
Use Prestitigator for +1 Quick Fingers

~~Underbelly~~

again, no interactions or talk, just pick up the shins in the sticha area (Northwest & southwest): 2x 13 shin, 1x 17 shin

~~Cliffs edge

again no interactions or talk, just pick up the shins in the SW and north: 22 shin, 23 shin, 34 shin

~~Circus Minor~~

Talk to the merchant Prata (S):
- Never visited this city...
- Still finiding my way... (get discount)
- use discount to sell enough to get 425 shins
I like to keep oddities, sometimes they do have a use (or reveal new information with more lore)
Sell cyphers (except shimmering glass & fresh vapors), unneeded weapons, spray flesh. -> just enough to get 425 shins

~~Cliffs Edge~~

follow the cliffs to Madelia Glittering (3 globes around head) and ask to see her items
Buy "Scholarch's Archive" Bonded Item - +1 Lore Machinery, +1 Lore Nature, extra esotery damage, negatives are supressed by our Concentration skill
-> equip (now we have 1 point in each lore skill)

Find Jerenaugh (Platform NE)
- hey the day is young (silver tiny)
- show me your items
buy the eye implant for 110 shin : 5 damage and +1 Perception

In the North (next to stairs) there is a crumbled house you can interact with. Killing the boss thug yields no loot or XP, so may as well use the "family man" line to make him back off (if a no effort persuasion check fails)
Gain Companion: Rhin

~~Circus Minor~~

SW talk to Tol Magur
don't give Rhin to her but keep talking
use multiple option to explain whats wrong with using rhin, persuade her
-> farwell after she teaches you: Tidal Affinity+1 (delay talk to later with full skills array)

Talk to Chandu (1st) and El-Jinto (2nd) at the glowing cage in the center
-> dialogue xp should be enough to get unlock tier 1 advancement: take Skill: Anamnesis

Close to the glowing cage in the center, there is a character called Steristi
-> Watch her work -> Lore:Nature notice how she works and tell her about it -> get "Amulet of the Eternal Traveler" > equip for Flex Skill (choose +1 in an exploration/lore/conversation skill)
-> activate to persuasion+1 (but could be any exploration, lore or conversation skill, can be changed after rest)

~~End Result~~

Skills on Trained before any quests (except the one required for Tidal Affinity):
Amnesias, Concentration, Cypher Use, Deception, Lore Machinery, Lore Mystical, Lore Natural, Perception, Persuasion (via Flex Skill), Quick Fingers, Stealth, Tidal Affinity

This is how my character screen loocked like:

Getting specialized for the most important skills fast

* On Tier 2 of nano, make sure to get the ability "Datasphere Link" which increases all lore skills by +1 to specialized, enough to unlock all Lore passives.
* If you solve the quest concering certain diggers in a amicable way without tribute, you get an artifact with +1 perception (for 2 perception)
* Tier 2, first unlock should be skill Anamnesis+1

Now the more common passive skills are all ready in Sagus Cliffs already...

General build suggestions
ignore pool increases on level up, always get edge: intelligence on the first 4 tiers. Doesn't have priority, but get is before the next tier (available 1/tier). That way increasing the Intelligence pool with conversations & items only won't matter. Since many skills, your weapons and your Esotery attacks are based on int, getting a free 4 effort will be enough in most cases. If that is not enough in combat, get the Nano ability "Targeting Eye" for another +15% hit chance.

Focue Descriptor

Brandishes a Silver Tongue
might seem like the obvious choice, but its actually not that impressive:
* Natural Charisma only increases max Effort but doesn't improve the checks. Better unlock more effort for all skills.
* Dealmaker: 5% is ok, but nothing major and i didn't suffer from money problems without
* Inspiring Presence: +5% to everyone & every skill check is really good in theory - in practice its helpful, but not really needed.
* Sow Dismay: Demoralized is an ok Fettle, but i'd rather use my action for AOE damage or a straight kill
* Invigorating conversation: Decent but a bit late - in Tier 4 with 4 edge and good equipment, you will barely need to spend intellect points

Breathes Shadow
great if you want to focus on stealth, my 2nd favorite.

Master's Defense
my favorite, for one main reason: Armor expert allows a Nano to use medium armor without any penalty, and the best Nano armor happens to be medium. Also adds another +2 to armor for extra resilience. Shield master for extra +10% evasion dosn't hurt, Bounceback as extra melee protection. While the action abilities are not worth it (Actions are used for Nano attacks), this will make our Nano really hard to kill. Combine with upgraded Oom Armor and you are truely godlike in resilience