Sengoku Jidai — Rules Guide

An HKCU game powered by Aornos Simulations, designed by Hobbes

This guide explains how the game works mechanically. For instructions on submitting orders through Discord, see the Player Command Guide.

Section 1: Turn Structure

Each turn represents a period of activity in feudal Japan. Turns are grouped into seasons, and seasons into years.

Seasons

Each turn, every character submits one order. At the end of the turn, all orders are resolved simultaneously in a fixed sequence, and the game state advances.

Section 2: Resources

Mon (Currency)

Mon is your clan's spendable currency, held in the clan treasury. It is spent on military recruitment, buildings, and special actions. The main source of Mon is taxing your provinces.

When you tax a province, you collect its entire Tax Stockpile plus any Mon Bonus (a flat bonus set by buildings in that province). The stockpile then resets to zero and begins regenerating next turn.

Knowledge

Knowledge is your clan's accumulated learning. It fills a shared pool and, once you reach certain thresholds, converts into permanent tech levels across five disciplines (see Section 5). You gain Knowledge from trade missions, meditation, experiments, and certain buildings.

Tax Stockpile and Manpower Stockpile

Every province generates two stockpiles each turn:

• Tax Stockpile — collected as Mon via /econ tax-province
• Manpower Stockpile — converted into military units via /econ recruit-levies

Both accumulate by their Regen value each turn, up to their Cap. Uncollected stockpile stays in the province up to the cap — you lose the overage.

Section 3: Provinces

Province Types

Provinces are either City or standard (rural). Cities have higher base Tax and Manpower values. Your clan has one designated Capital province, which receives additional bonuses at higher tech levels.

Province Stats

All caps and regen values are recalculated at the start and end of each resolution — whenever you build a new building or gain a tech level, it takes effect in the next resolution.

Connections

Provinces are connected to neighbors via adjacency links. Armies can only move to connected provinces. Province adjacency is stored in the Province Tracker and is also what determines autocomplete options in /army lead-army.

Section 4: Buildings

Building Slots

Each province has 4 building slots. A fifth slot unlocks when your clan reaches Development 3. Only one building can occupy each slot.

Buildings are divided into three types:

• Universal — can be built in any province
• City — can only be built in City provinces
• RGO — can only be built in provinces with a matching resource type

Building Effects

Unit Production

The buildings in a province determine what unit type is produced when recruiting levies there. The first applicable building wins:

Economic Buildings

Knowledge & Research Buildings

Military Buildings

Building Costs

Building costs are set in the building data. Two things can reduce them:

• Expansion 1+: −1 to all building costs (province-wide)
• Workshops building in the province: −2 to all building costs

Section 5: Knowledge and Technology

How Knowledge Works

Your clan accumulates Knowledge in a shared pool. Once the pool reaches a threshold, it converts into a permanent tech level in one of five disciplines. Tech levels are cumulative and carry forward.

Choosing Which Tree to Advance

When your clan earns a new tech point, you choose which of the five trees it goes into. The bot handles this through Discord buttons after each resolution. If your clan has any unallocated points, the bot posts a prompt in your clan's capital channel with five buttons — one per tree — showing each tree's current level. Your Daimyo or Shikibu Kyo clicks the tree they want to advance. If multiple points are available, the bot loops: after each selection, a new prompt is posted until all points are allocated.

If a prompt is missed (e.g., the bot restarted), an admin can run /tech-check to re-issue it.

Tech Tree

Section 6: Military

Unit Types

Armies

Units are grouped into named armies. Each army has a location and may have a leader (a character from your clan). When units are recruited in a province that has no existing friendly army, a new army is automatically created.

Multiple armies from the same clan can exist simultaneously in different provinces.

Army Movement

The /army lead-army command moves an army one province along an adjacency link. The character leading the army moves to the destination with it.

Crossing-path conflict: If two non-allied armies attempt to cross each other's path simultaneously (A→B while B→A), the larger army wins and completes its move. The smaller army is blocked and stays at its origin. On a tie, cavalry count is the tiebreaker, then a coin flip.

Post-Resolution: Battle Resolution

After all orders resolve, battles are processed automatically. Any province containing armies from two or more non-mutually-allied clans triggers combat. Mutually allied clans fight on the same side; all other clans form opposing sides. Alliance requires mutual declaration — both clans must have declared each other as allies.

Combat Strength (CS)

Each army's Combat Strength is calculated at battle time:

Samurai pool bonus: min(basic_units ÷ 3, samurai × cap), where basic units is all non-Samurai non-Siege units and cap is 3 (or 5 with Piety 5+).

Damage Formula

Each side rolls a d20. The side that moved into the province this turn is the attacker; the side already present is the defender (if both or neither moved, the larger CS side is attacker).

Damage = ROUND((terrain_modifier + d20 roll) / 100 × CS)

Terrain modifiers (attacker / defender):

Damage is distributed proportionally across all armies on the receiving side. Within each army, Spear Levies are removed first, then Sword, Archer, Cavalry, Firearm, and Samurai last.

Retreat and Destruction

An army that loses more than 50% of its units in a battle is forced to retreat:

• If it moved into the province this turn, it retreats to its origin.
• Otherwise, it retreats to the nearest adjacent province it can reach safely (BFS search — no hostile armies there).
• If no valid retreat exists, the army is destroyed (all units zeroed out).

Province Capture and Pillage

When all opposing sides are forced to retreat or destroyed, the victorious side captures the province:

• The Controlled by field changes to the winning clan.
• The province's Tax Stockpile is immediately pillaged and added to the winner's treasury.

Piety 5 — Cannot be pillaged: If the losing clan has Piety 5+, the province control still transfers but the Tax Stockpile is not looted.

Note: Capture changes Controlled by (who can tax and administer the province), not Province Owner (the political map).

Siege Weapons belonging to a routed army are transferred to a surviving enemy army.

Leader Death

If a leader's army suffers 30% or more casualties, that leader faces a death roll. Probability scales from 10% at 30% casualties to 100% at 100% casualties. A killed leader is removed from the roster, stripped of their title and Discord roles, and announced in the graveyard channel.

Fortress Garrison and Siege

Provinces with a Fortress building have a garrison that can shelter defending units. Garrison capacity depends on Fortress level (level 1: 8 units, level 2: 16, level 3: 32, level 4: 64). Piety 4+: no unit cap — all defending units can enter the garrison regardless of capacity.

Fortress Pre-Check

At the start of a battle, if the defending side's CS is lower than the attacker's, defending units automatically move into the garrison (highest-value units first, up to capacity). If all defending units fit inside, no open battle occurs — a siege begins instead.

Siege Mechanics

A besieged fortress has a Siege Timer (3 turns by default; 4 turns if the defender has Piety 5+). Each turn, the timer decrements by one. If the besieger has a Siege Weapon, it is expended to reduce the fortress level by one (if reduced to 0, the fortress is destroyed and the siege ends immediately).

When the timer reaches 0, the garrison surrenders: units are disbanded and control of the province transfers to the besieger.

Winter (Turn 9)

Winter imposes two automatic effects that cannot be avoided through orders:

Army Attrition

Before orders resolve, every army suffers losses from the cold. The base loss rate is 60% of total unit count (rounded up). Units are removed in order from weakest to strongest:

1. Spear Levies
2. Archer Levies
3. Sword Levies
4. Cavalry
5. Firearm Levies
6. Samurai

Siege Weapons are never lost to attrition.

Warfare tech reduces the loss rate:

Movement Blocked

All /army lead-army orders are cancelled during Winter resolution. Characters who submitted a lead-army order receive a notification and their character is moved to the army's current location, but the army does not move.

Ownership Consolidation

At the end of Winter resolution, every province that has a Controlled by value (i.e., captured territory held by someone other than the original owner) transfers full Province Owner status to the controlling clan. This takes effect at the start of the next year.

Post-Resolution: Hostile Army Presence

If a character ends a turn in a province that contains a hostile army (from a clan not mutually allied with theirs) and no friendly army is present to protect them, the character has a 10% chance of death. A friendly army in the same province negates this risk.

Section 7: Characters and Authority

Titles

Each character has a Title: Daimyo, or another title held within their clan. The Daimyo is the clan leader and has access to special commands (setting orders for clanmates, executing characters, designating allies).

Authority Score

Authority measures a character's political standing. It affects Daimyo succession contests, Shogunate claims, and the difficulty of executing others.

Authority Changes by Mission

Each mission changes the acting character's own Authority in addition to any other effects:

Claim Daimyo

When a character submits /social claim-daimyo, they challenge the current Daimyo at turn resolution.

If multiple clanmates attempt a coup in the same turn, only the one with the highest Authority gets to challenge. The rest have their orders cancelled.

Resolution:

1. The higher-Authority challenger wins. On a tie, a coin flip decides.
2. The winner becomes Daimyo.
3. The loser takes a flee check (d20):

Flee threshold = 10 − (winner's Authority − loser's Authority) + modifiers

Minimum threshold: 2. Maximum: 18.

• Roll ≤ threshold → Loser flees. They are assigned as leader of a leaderless clan army outside the capital, or exiled to a random province within 2 hops of the capital if no such army exists. Their Daimyo title and clan role are stripped.
• Roll > threshold → Loser dies. Marked dead; title, clan, and Discord roles removed; announced in the graveyard.

When the usurper wins, the change is announced publicly. When the Daimyo successfully defends, no announcement is made.

Claim Shogunate

The Shogunate is the supreme political position in the game. Only a Daimyo can claim it. If a Shogun already exists, the claimant must satisfy all three of the following:

• Their clan owns 25% or more provinces than the current Shogun's clan
• Their clan has 25% or more deployed units (total across all armies) than the Shogun's clan
• The claimant's Authority exceeds the current Shogun's

If multiple clans qualify simultaneously, the one with the highest province count wins (tiebreak: Authority).

Benefits of holding the Shogunate:

• Character cap increases from 4 to 5
• /army rally-samurai recruits up to 5 Samurai at 6 Mon each (vs 7 Mon for /army hire-samurai)

Section 8: Diplomacy

Alliance

Clans can declare others as allies via /clan designate-ally. A declaration takes effect at turn resolution, not immediately.

Alliance is one-sided by default: declaring another clan your ally does not mean they have declared you theirs. The game tracks these separately.

Mutual alliance (both clans have declared each other) has gameplay effects:

• Mutually allied armies do not trigger a battle when they share a province
• Army crossing-path conflicts do not occur between mutually allied armies

A one-sided declaration does not prevent battles — only mutual declarations do.

Declarations can be made secret (not announced in #world-declarations) but still take effect mechanically.

Establish Relations

The /social establish-relations order creates a private Discord text channel between your clan and the target clan.

Resolution:

• A new text channel is created under the diplomacy category, named "Your Clan - Target Clan"
• The channel is private: @everyone is denied access; both clan roles are granted view, send, and read access
• The channel has a 2-hour slowmode
• Both clan roles are mentioned in the channel on creation
• Both clans' orders channels receive a notification that relations have been established

If a channel for this pair already exists (in either name order), no new channel is created. The mission still completes and Authority is still awarded.

The Shogunate begins the game with channels open to all other clans.

Section 9: Execution

The /clan execute command is a free action (does not use the character's turn order) available only to the Daimyo. It submits an execution order to the queue, which is processed before mission resolution each turn.

Valid Targets

• Any member of your own clan, regardless of their location
• Any foreign character currently located at your capital

Resolution

Execution uses a d20 roll. Success if roll ≤ threshold.

Base threshold: 18 (modified by the authority difference between executor and target, capped at ±5)

Threshold is capped between 1 and 20.

On success: Target is marked dead. Their title, clan, and Discord roles are removed. A public announcement is posted to the graveyard channel (unless the execution was secret).

On failure: The executor receives a private notification. If the execution was public (not secret), the target receives a notification that they were the subject of an assassination attempt.

Only one execution attempt per Daimyo per turn is processed.

Section 10: Letters

Characters can write letters to other clans via /letter write. Letters are not delivered immediately — they are staged as "Pending" and dispatched during turn resolution.

Dispatch Rules

Your clan's Learning tech level determines how many letters are sent each turn:

Letters appear in each clan's private thread in the letters channel.

Section 11: Summary of Derived Stats

The game automatically recalculates derived province stats before and after each resolution. You never need to compute these yourself — they update in the Province Tracker when any input changes (buildings, tech levels, province ownership).

Province Stats Formula Reference

Tax / Manpower Regen:

• Base: 2 (City) or 1 (rural)
• +1 if Development ≥ 4 and the province is a City
• +1 if Development ≥ 6 and this is your capital
• +1 if the province has Large Fields

Tax Stockpile Cap:

• Base: 4 (City) or 3 (rural)
• +1 if Expansion ≥ 5
• +5 if Development ≥ 5 and this is your capital
• +2 Fishing Village, +2 Treasury, +1 Storehouse

Manpower Stockpile Cap:

• Base: 4 (City) or 3 (rural)
• +1 if Expansion ≥ 5
• +5 if Development ≥ 5 and this is your capital

Mon Bonus (collected alongside tax stockpile):

• Gold Mine: +2
• Silk Weavers: +3
• Mining Village: +1
• Court: +1 per province your clan owns at time of recalculation

Levy Bonus (extra units when recruiting levies):

• Fields: +1
• Barracks: +2

Building Cost Reduction:

• Expansion ≥ 1: −1
• Workshops: −2