I recently mixed Scarlet Heroes with Whitehack (more about that here) and I want to try out how it works. I made two characters, a Deft one (skill monkey) and a Wise one (magic-user).
I use Scarlet Heroes’ solo engine for an urban adventure in Xian, the Imperial city of the Red Tide setting (included in the Scarlet Heroes book, plus there is a separate setting book (aff) with the same name).

Characters

Otori, Deft Mercenary
STR 12 (0), DEX 16 (+2) (Halfling), CON 12 (0), INT 11 (0) (Halfling), WIS 10 (0), CHA 10 (0)
HP 4, AC 7, AtB +1, Fray Die 1d6
Leather Armor, (Short Sword 1d6), Sling 1d4, (Dungeoneer Gear), 20gp

Sylvan, Wise Elementarist
STR 13 (+1), DEX 16 (+2), CON 16 (+2), INT 8 (-1) (Guild of Magicians), WIS 17 (+2) (Elementarist), CHA 4 (-2) (Red Tide Cultist)
HP 6, AC 9, AtB +0, Fray Die 1d4 effects all
No Armor, Bow 1d4, Knife 1d4, 40 gp
(Fire Bolts), Fire Elemental, Water Elemental, Water Spray

About the system

It’s an old school D&D system, basically Scarlet Heroes with some tweaks from Whitehack. As you can see, each character has the classic six attributes and attribute modifiers. The classes were taken from Whitehack. The Deft is a Mercenary and may use bonus rolls when doing things related to that. He is also actively attuned to his short sword (and inactively to Dungeoneer Gear). That means if he uses his short sword, he also gets a bonus. He is a halfling, that gives him something positive for DEX but he needs to roll a negative double roll when using INT.
The Elementarist has slightly better attributes, save INT and CHA and is affiliated to the Guild of Magicians. Because his CHA is so low, he gets a drawback and I decided that he is corrupted by the Red Tide, a magical mist from the setting.
Magic in Whitehack works with miracles which are free-from magic tags. He is an Elementarist and gets a positive double roll related to WIS and has an active spell called Fire Bolts. The other spells are inactive. He can change slots, but it will take time.

Scarlet Heroes has a simple skill and saving throw system. You roll 2d8, add the most relevant attribute modifier. For a saving throw, you additionally add your level. The original Scarlet Heroes system uses Traits which I dropped in favor of the Whitehack system.
Armor class is descending. For an attack roll, you roll d20+Attack Bonus+opponent’s armor class and need to meet or exceed 20. That’s pretty easy to understand and makes descending armor class intuitive (no need to consult tables).
Furthermore, there are some tweaks to damage. There is a table for how much damage each roll does. Damage is done directly to HD, you don’t roll the Hit Dice to get Hit Points. Heroes also have a Fray Die which does bonus damage.
As a result, 1st level characters are already pretty sturdy.

Scarlet Heroes also has a solo system for urban adventures with lots of tables, so I’m using it for my solo urban adventure.

Urban Adventure in the Red Tide Setting

Setup

rolled up on the Plot table of Scarlet Heroes:

Plot No 2: An Antagonist seeks to steal something precious to a target

target (rolled on the Actors table): Elderly Crafter, race: human, Imperial & Eirengarder, relationship: lover

An old lover of Otori, Elsa, a human of Imperial and Eirengarder descent, has recently crafted a pair of glasses with almost magical properties. These glasses were capable of sensing Red Tide corruption. Now they were stolen.

Victory Points: Heroes: 0, Opposition: 0
Threat Level (T): 3 Heat: 0

The first to get 10 Victory Points (VP) wins. When you win a scene you get one to two VPs. You start out with 0 VP. You can adjust the Threat Level to your liking from 1 to 10. I chose 3 as an easy entry point. Heat is a measure of how much ruckus you cause in town. It starts at 0 but every time you do something which will cause attention, you need to make a check to see if Heat rises. If you accumulate too much Heat there will be adventures where you have to cope with the consequences.

Investigation Scene

rolled on the Investigation Scene table:

Search a Location related to past events where a Clue can be found. Roll a die; on an odd result, you face a Fight whether or not you succeed on your check.

(A Clue is an in-game currency. You gather Clues to incite an Action Scene. There are three types of scenes: Investigation Scenes give you VP and Clues. If you want to instigate an Action Scene, you need to spend one Clue. Action Scenes grant 2 VPs per overcome challenge. Conflict Scenes reduce the enemy’s VP if you are successful and get another VP yourself.)

Die roll: even
Location (rolled on the location table): Moneychanger

Our heroes got a tip that recently someone changed a great sum of money at Sungeh’s. Sungeh runs a small money changer shop in one of the lower districts and seldom someone comes with such an amount of gold. Very suspicious.

How is the relationship to Sungeh? 1d3: 1 = friendly, 2=stranger, 3= unfriendly
roll of 2 = stranger
roll on the NPC reaction table for NPC stranger: 7 = bribeable

Sungeh insists on the privacy of his clients. Otori slips him 5 gp and asks if he can’t make an exception. With that bribe he makes a CHA skill check against 9+half the Threat Level (T) = 10
result of 12, success

Let’s roll on the Actors table to see who the culprit may be:
It’s a wealthy heir.
Hmm. The heir has fallen out of grace because he shamed his family with his behavior. Now they shun him and his money has run out. To finance his lifestyle, he might have stolen Elsa’s device.
Name (from the Red Tide setting book): Tang Renshu
So, Sungeh heard how others called this nobleman “Noble Tang”.

End of scene:
Heroes gain 1 Victory Point + 1 Clue roll a d10 to see if opposition gets a VP, too: 5 (higher than number of Investigation and Action scenes, so no)

Action scene

You can always incite an Investigation scene or a Conflict scene if you want. To play an Action scene you have to spend 1 Clue (you get one 1 Clue as a result of winning an Investigation scene). Action scenes are good for getting Victory Points, as you get 2 if you win a scene.

Let’s spend the Clue right there to further the plot.
roll of 5 on the Action Scene table:

Plunder resources necessary to the foe’s plan. Either make a check at +2 difficulty or face a Fight instead of a check.

Let’s try to fight instead of being suble.
Where does it take place (roll on Locations table)? Tavern

The game gives you rules for rolling the opposition and its difficulty: Fight Difficulty (roll on table): 1d8+1 (1/2 Threat Level) = 9
that means 1 Tank + 3 Thugs (1d4+T)

Tank: 2 HD, AC 3, +Hit +2, Dmg 1d8, Morale 10, +Skill +2, Move 20’ 3 Thugs: 1 HD, AC 8, +Hit +1, Dmg 1d6, Morale 8, +Skill +1, Move 30'

The Silent Hedgehog is a seedy tavern in one of the poorer parts of Xian. Sungeh suggested that the heroes visit this establishment as the nobleman had some thugs with him who are frequent visitors of this pub.
Entering the shady alehouse, Otori and Sylvan are immediately greeted by unfriendly stares by 4 brutes.
“We are looking for a nobleman of the Tang family. You don’t happen to know one?” asks Sylvan in an amicable manner.
Unfortunately, his ugly Red-Tide corrupted face, doesn’t inspire friendliness and the thugs stand up from their bar stools and draw their weapons.
While the tavern owner, an elderly Imperial, withdraws with a hasty: “Don’t break anything, you’ll pay for the damages!” Otori and Sylvan realize that this will end in violence.

Combat

Round 1

Sylvan casts a firebolt up the ceiling, so that the big oil lamp will come crashing down on the foes. That works as intended for a HP cost of 1 (Sylvan is down to 6 HP). One of the fire bolts strikes down one of the thugs (result of his Fray Die showing a 3 which makes 1 point of damage).
The thugs get a saving throw to evade the oil lamp (difficulty 10). The tank & 1 of the remaining thugs succeed, but the other one gets hit by the lamp and the engulfing flames and is out of the fight.

Otori attacks the biggest brute with his short sword and slashes him (1 point damage, the brute is down to 1 HD). With his leg he kicks the other one swiftly and knocks him out cold.

Oops, quite effective, these two. Only the big brute is still standing. Morale check, roll of 7 (less than the morale of 10).

With a roar the big fellow grapples Otori (natural 20) and tries to break his neck (1 point of damage, Otori is down to 3 HP).

Round 2

Otori tries to break free, opposed strength check, the thug wins.
Otori can’t use his Fray Die because the opponent has a higher level.

Sylvan throws his knife, roll of 15 + Attack Bonus 0 + opponent’s AC 3 = 18, not enough (he needs 20 or more).
But the flames are growing higher now and reach the brute (1 point damage from the Fray Die (roll of 4)).

With a cry, he lets go of Otori.

End of fight

So, after some commotion the two adventurers put out the fire and can now question the remaining nobleman’s hireling.
Otori binds his wounds and is back to full HP (4), Sylvan can’t bind wounds created by using magic.

End of Scene:
Heroes gain 2 VPs, opponents get none (roll of 3, that’s more than the sum of Investigation & Action scenes so far (2)).
Heroes: 3 VPs opponents: 0 VPs

As the challenge was beaten in a flashy style, I need to roll for Heat. roll 1d10 = 5
The rules say to compare it to the highest spell used in the challenge. If it’s higher, you gain 1 Heat. My hack doesn’t use spell levels but as the adventurers are level 1, I guess that the spell level is somewhere in this range, so no Heat for my adventurers.

What would be next

As I have no Clue left, I can only make an Investigation or Conflict Scene. A Conflict Scene reduces the opponent’s VP but as the opposition doesn’t have any, it’s not a good move. So an Investigation Scene in hopes of gaining another Clue would be my next step.
The game would continue until one side reaches 10 Victory Points.

Whitehack Heroes is a serviceable gaming system and works fine for someone familiar with both systems.

Links:
Scarlet Heroes (aff) WhitehackWhitehack Heroes Red Tide Campaign Setting (aff)