General:
I’ve played Arcanum: Of Steamworks & Magicka Obscura on and off for about 10 years. I know about plenty of bugs and abuses that make finishing the game pretty fast. When I came across Bioman's [00:11:32] run of the game. I was able to get the last pieces of the puzzle to make this run possible. This run is a single-segment and uses the last official patch (1.0.7.4).

Character:
The exact race/background combination does not matter that much. It's possible to achieve similar things with different things. It is important to have 12 Intelligence, 9 Willpower and 6 Charisma. You want to have a decent amount of Constitution and Dexterity and the rest doesn't matter. So if you can accomplish that with a background + 2 skill points that'll work. The other 3 points go into Persuasion (1) and College of Fire (2). I need 12 Intelligence to have 3 active spells, 9 Willpower to open up second level spells and 6 Charisma to get the first point in Persuasion.
The character in the run is a Female Half Elf with the Sheltered Childhood background. I put 2 points in Intelligence, 1 point in Persuasion and 2 points in the College of Fire.

The run:
Before the run started I set the difficulty to hard and combat to Fast Turn-Based(FTB). FTB allows me to jump from location to location without movement. You have to be in combat mode though so you'll lose fatigue points. This and the fact that when you enter combat it is always your turn let's me skip most enemies I encounter. In addition it is possible to change between real-time and turn-based by pressing spacebar. This makes the 3 fights very quick.
Sometimes I click buttons on the UI instead of using the hotkeys. I do this because moving the camera with the arrow keys is faster than with the mouse. Sadly I can't press both hotkeys and arrow keys with my hand in one spot. So I have to balance the time my left hand is in what position.

Crash Site/Shrouded HIlls
I start off skipping through Virgil's dialog. If you have very high mouse precision you could decline him joining you from the starting dialog though for me it is faster doing it afterwards. I enter combat mode and go southeast to the exit of the crash site. FTB allows me to skip the encounter with the robed elf because the scripted tile doesn't trigger correctly. In Shrouded Hills I sprint to the gipsy to buy three items: Essence of Intellect, Light Fatigue Restore and a Potion of Haste. I persuade the thieves for two reasons. First it is faster than killing them, secondly I get some extra cash I need for the train. On the bridge I skip another scripted tile.

Tarant/Black Root (waypoint glitch)
I put my marker on the location of Tarant and I start fast travel. I get four encounters while fast traveling, which is actually unlucky. To leave those encounters I enter combat by pressing R and hop out of range. It might look like I am just standing there, actually I am mashing W (World map). I do this for every worldmap encounter.
In Tarant I hop across the bridge to the Steamrail Station. It is important to avoid accidentally clicking the guard and dieing. Using the Steamrail I can fast travel to the Vermillion Station. There I buy a ticket to Black Root.
Now I walk out of Tarant to get to the worldmap. I put my marker in the south east of the Morbihan Plains. The precise position does not make a difference; only the general area matters. This is part of what I call the waypoint glitch. Now I exit the world map go back to the Train Conductor and handle his dialogue. I leave Black Root and start fast traveling. Now I can fast travel and I'll be headed to Thanatos.
This is possible because the game remembers you map markers, direction and distance but when you travel without using the world map the marker doesn't disappear. This makes it possible to reach islands not intended to be reached, or as seen in the run Thanatos without rushing Stringy Pete. It is important to not let the fast travel finish because you will suddenly be in the spot you marked. It is not possible to reach Nasrudin directly. There is not enough landmass south east of Tarant.

Thanatos
I cancel the fast travel on Thanatos and set my route to the Landbridge. On the first random encounter I am not able to get out of range so I have to switch to real-time and walk away. This is onfurtunate. The second encounter is fine.
In Landbridge I put 3 Agilities of Fire on my self. With 3 speed buffs I cap out Dexterity at 21. Makes it easy to move past any monkey without being attacked. When an enemy is near I leave and enter combat mode. With 20+ action points it's very unlikely I'd still be in range after moving. I have to leave combat mode because I don't want to be low on AP when I get engaged. Halfway through I use the fatigue potion.
Before Nasrudin I have to leave the zone to sleep. This restores fatigue and gets rid of the active spells.

Nasrudin Fight
Next I blitz through Nasrudin's dialog and cutscene to get free experience. Using a fate point I can easily steal his staff. I need the staff for extra mana, although it might be possible to finish without the staff. I enter the character screen and get the Orcish Champion summon.
During the fight I am supposed to resummon my orcs if necessary, put the two fire spells and the orc summon on my quickbar, and equip the staff. I need to use the Orc Summon to kill him, because Nasrudin has Disintegrate, which instantly kills me. It's random if he uses it or not. Using multiple Walls of Fire will kill him faster but it's extremely rare to not get disintegrated by this fool.
The fight is pretty quick and with Nasrudin dieing I get into the Void.

Void
I sleep to get rid of the summons and restore fatigue. Then I apply three Fires of Agility on myself and drink the potion of haste. Now I had to Arronax and before him I skip two lines of dialogue with FTB. Arronax gives me the remaining experience to complete the run and I rush onward to get Kryggard's Falchion. You need it to defeat Kerghan. (Or the Vendigroth Device, which lies out of reach)
Without the potion of haste the cave is very tricky to do but it is still possible. Especially the part with the flying jellyfish where you grab the sword. It can be done by creative switching between real-time and turn-based combat, but the speed hoarding is faster and easier. When I have the Falchion I run back through masses of enemies unharmed again past Arronax. Anyway before the fight with the guards I rest, grab Entangle from the College of Nature and drink the Essence of Intellect to allow me having 5 active spells.

Door Fight
For a long time this was my most inconsistent part of the run. As I do it now I can pull it off unharmed, but based on RNG it can take longer. The guards have a summon spell for a minion who can cast harm. Harm is an instant damage spell with no range limit and since I am not very tough I die instantly if they can cast it on me. To circumvent this I bait them with a summon. I have very good fortune and am able to entangle them on a row three Walls of Fire on them at the same time.
Also I want to note that you can't entangle both of them from the starting position because the lower one is standing on blocked terrain. Which makes it impossible to put a Wall of Fire on him where he is at the start.
After I have dealt with this mess I rest and again put 3 speed buffs on me to make the final FTB section

Kerghan
I just run through Kerghan's castle nothing really exciting happens.
Now the final boss, Kerghan. I just summon 3 orcs to hit him while the Lord's Slaves damage him. At the start I use entangle on him even though I have no empty active spell slot. It still stops him for a second and he switches target. Meanwhile I equip the Falchion and put my final points in; Strength of Earth and Melee (2). Now before he gets in the shield I put 3 strength buffs on me.
The strength is required to hit harder and the melee is needed to lower the chance to critically miss and die. (This has happened a lot.)
When he gets in his regenerative shield he is immune to anything except the sword so I have to melee him. When the cutscene starts the game is over.

https://www.youtube.com/watch?v=xbU3KD0ci-g
 
DETAILS:
 
Before starting:
 
- I show you the options used: Easy mode means more exp and character points to spend, although it could've been done on Hard as well with little differences; Fast Turn Based on start means I can jump right into FTB running, see this for more info:
http://arcanum.wikia.com/wiki/Bugs_and_Glitches#Fast_Travel_Trick
- I make my character: custom portrait of my avatar, name Daegon, race Half-Elf, background Sheltered Childhood
- I distribute 2 character points in the Fire college, 2 character points in the Conveyance college (for Unlocking Cantrip) and 1 point in Persuasion (for ridding of Lukan without going through combat)
-I sell the suit I start with - mages don't wear suits - and buy myself some decent robes instead, I also buy a Light Fatigue Restore potion and place it in the toolbar which isn't visible on the interface yet but still functions
-I skip through the cutscenes, and the run starts just as Virgil's dialogue is initiated
 
Segment 1:
 
-I hit A which is the hotkey for last action used, by default this is set to the Pick Pocket skill on start which effectively skips Virgil's dialogue. It is a variation of this exploit:
http://arcanum.wikia.com/wiki/Bugs_and_Glitches#Toolbar_Dialogue_Skip_Exploit
- I enter FTB combat mode and run to the world map exit, skipping the Molochean Hand assassin along the way (since he managed to spawn in, Shrouded Hills is marked on my map now)
- I travel to Shrouded Hills
 
Segment 2:
 
- I run to the Wise Woman and buy a Potion of Haste, which in hindsight I didn't even need later on but it still slightly helped getting through Kerghan's Castle
- I rush through Lukan's dialogue, he gives me some gold and I'm set to leave. Before exiting on the world map, I skip another Molochean Hand assassin via to the aforementioned exploit.
 
Segment 3:
 
- Travelling to Tarant (which isn't even marked on my world map) without any encounters on the way. This is what segmented speedrunning helps with, among other things
 
Segment 4:
 
- I get to the railway and travel to Vermillion Station
- I talk to the Ticket Seller and buy a ticket to Black Root
- I go north of Tarant on world map and set a marker which I will need later on for this exploit:
http://arcanum.wikia.com/wiki/Bugs_and_Glitches#World_Map_Waypoint
- I talk to the Mage's Caboose Conductor and travel to Black Root (segment doesn't end here yet because reloading a save will remove the marker I set earlier from the world map)
- Once in Black Root I rush to the mage's shop and wait until evening + 2 more hours for the doors to her bedroom to unlock (creepy, I know)
- Inside I wait until morning for her to return to her original standing point
- I use a Fate Point on Spell at Maximum and cast Unlocking Cantrip on the vendor's chest. Because the fate point I just used gave me 100% Magickal Aptitude for that one spell, the chest is unlocked and I can take the stuff I will need later: some fatigue potions, Body of Water scroll and a Mage Staff (50 mana pool when equipped). I was originally going to identify the staff using a Divine Magick scroll found inside the same chest so I can use Dweomer Shield for the battle before Kerghan's Castle, but realized that would prevent me from casting any spells.
- I wait again for the door to unlock, and run towards the world map
- Because of the marker I set earlier, I can now glitch over the ocean to Thanatos
 
Segment 5:
 
- I travel halfway between Land Bridge to avoid random encounters
 
Segment 6:
 
- I travel from that point onward to Land Bridge
 
Segment 7:
 
- I equip the staff, cast 2x Agility of Fire and use a Potion of Haste
- I rush to Nasrudin's Resting Place and use a fatigue potion along the way
 
Segment 8:
 
- I sleep just outside Nasrudin's Resting place at the world map to get rid of my buffs and restore mana/fatigue
- Character point allocation and fight against Nasrudin with 3 summoned Orc Champion
 
Segment 9:
 
- Sleeping in the Void to get rid of summons and restore mana/fatigue
- Buffing with some Agility of Fire to make this part faster
- Running to Arronax's Prison
 
Segment 10:
 
- Skipping through Arronax's dialogue for exp
 
Segment 11:
 
- Character point allocation and toolbar placement

Segment 12:

- Sleeping before Kerghan's Castle in preparation for battle

Segment 13:
 
- Fight against 2 guards outside Kerghan's Castle:
- I summon an Orc Champion to distract them while using Entangle and Wall of Fire on each guard, buffing myself with Essence of Intellect along the way so I can sustain more spells
- I move away for a bit so their summon doesn't instakill me
 
Segment 14:
 
- Running through Kerghan's Castle while buffed with 3x Agility of Fire and Potion of Haste
 
Segment 15:
 
- Skipping Kerghan's dialogue with the toolbar dialogue exploit
 
Segment 16:
 
- Battle against Kerghan:
- I summon 3 Orc Champion to deal damage while he attempts to fight back with summons. I entangle the summons which I suspect will be targetting me and the rest switch target on Kerghan (bug)
- Once Kerghan enters his regenerative shell, I use Body of Water on him which removes the invulnerability flag, allowing my summons to kill him - yes, neither the Vendigroth Device nor Kyriggird's Falchion are required!
- Run ends when Kerghan's death cutscene triggers