Modding Guide

TinyGenerals is data-driven — game rules, factions, and visuals are defined in JSON files and sprite sheets. This guide covers the format and structure you need to create custom content.

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Rulesets

A ruleset is a single JSON file that defines all game rules: terrain, units, buildings, factions, combat, and vision. The default ruleset is “Classic TinyGenerals.”

Ruleset Structure

{
  "id": "my-ruleset",
  "name": "My Custom Ruleset",
  "faction_mode": "optional",
  "faction_selection": {
    "required": false,
    "default_behavior": "prompt",
    "allow_mirror_matches": true,
    "auto_balance": false
  },
  "factions": { ... },
  "terrain_types": { ... },
  "overlay_types": { ... },
  "unit_types": { ... },
  "building_types": { ... },
  "vision_rules": {
    "mountain_vision_bonus": 1,
    "forest_blocks_vision": true,
    "mountain_blocks_vision": true
  },
  "combat_rules": {
    "base_damage_formula": "attacker.attack",
    "adjacent_only": true,
    "attack_model": "soft_hard",
    "terrain_bonus_enabled": true,
    "building_bonus_enabled": true,
    "terrain_building_stack": "max",
    "ambush_bonus": 25,
    "suppression_enabled": true,
    "global_suppression_ratio": 0.0,
    "pinned_threshold": 1,
    "friendly_fire_enabled": false,
    "friendly_fire_damage": 0.5
  }
}

Faction Mode

Value	Behavior
"none"	No factions. All players use the shared unit_types.
"optional"	Players may pick a faction for unique units.
"required"	Every player must select a faction before the game starts.

Shared vs Faction Units

The top-level unit_types defines generic fallback units used only when no faction is selected. In faction games, each faction’s own unit_types completely replaces any shared unit with the same key:

{
  "unit_types": {
    "INFANTRY": { "name": "Infantry", "role": "INFANTRY", "health": 10, ... },
    "VEHICLE":  { "name": "Vehicle",  "role": "ARMOR",    "health": 15, ... }
  },
  "factions": {
    "ALLIANCE": {
      "unit_types": {
        "INFANTRY": { "name": "Militia",     "role": "INFANTRY", "health": 10, ... },
        "VEHICLE":  { "name": "Battle Tank", "role": "ARMOR",    "health": 18, ... },
        "HOWITZER": { "name": "Howitzer",    "role": "RANGED",   "health": 10, ... }
      }
    }
  }
}

An Alliance player gets Militia, Battle Tank, and Howitzer — never the generic Infantry or Vehicle.

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Unit Archetypes (Roles & Tiers)

Maps are faction-agnostic — the map creator doesn’t know which factions will play. Spawn points use archetypes (a role + power tier) that resolve to the correct faction unit at game start.

Roles

Every unit definition includes a role field:

"HOWITZER": {
  "name": "Howitzer",
  "role": "RANGED",
  "health": 10,
  "min_attack_range": 2,
  "max_attack_range": 4,
  ...
}

Role	Description	Current units
INFANTRY	Foot soldiers, can capture buildings	Militia, Trooper, Shock Trooper
ARMOR	Heavy armored vehicles (tanks)	Battle Tank, Assault Tank
RANGED	Long-range indirect fire (artillery, rockets)	Howitzer, Rocket Battery
ANTI_ARMOR	(Reserved) Anti-tank / tank destroyers	—
RECON	(Reserved) Fast scouts with high vision	—
VEHICLE	(Reserved) Light vehicles (APCs, IFVs)	—
ENGINEER	(Reserved) Builders, repair, field fortifications	—
AIR_DEFENSE	(Reserved) Anti-air units	—
FIGHTER	(Reserved) Air superiority aircraft	—
BOMBER	(Reserved) Ground attack aircraft	—
NAVAL	(Reserved) Surface warships	—

Tiers

Units in the same role can have different power tiers:

"SHOCK_TROOPER": {
  "name": "Shock Trooper",
  "role": "INFANTRY",
  "tier": 2,
  "move_points": 4,
  "allow_move_after_attack": true,
  ...
}

Tier	Meaning	Example
1 (default)	Basic unit	Trooper
2	Advanced variant	Shock Trooper
3	Elite variant	(future)

Units without a tier field are tier 1.

Spawn Resolution

When a game starts, each spawn point resolves like this:

1. Direct match — If the spawn value is a unit ID (e.g. "HOWITZER"), use it directly
2. Role + tier scan — Find a faction unit with matching role and tier
3. Tier fallback — No match at requested tier? Try the next lower tier, down to T1
4. Last resort — No unit matches the role at all? Spawn the faction’s Infantry

Example: A map spawn is set to INFANTRY_2 (Infantry, tier 2):

Faction	Has T2 infantry?	Result
Federation	Yes (Shock Trooper)	Spawns Shock Trooper
Alliance	No	Falls back to T1 → Spawns Militia

Using Archetypes in the Map Editor

In the map editor’s Spawns mode:

1. Select a player slot (P1–P8)
2. Pick a role — Infantry, Armor, or Ranged
3. Pick a tier — T1, T2, or T3
4. Click hexes to place spawn points

The spawn marker shows the role letter and tier (e.g. I for Infantry T1, R2 for Ranged T2).

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Creating a Faction

A faction lives inside the ruleset’s factions block. Here’s the minimal structure:

"MY_FACTION": {
  "id": "MY_FACTION",
  "name": "The Ironclads",
  "description": "Heavy defensive faction with powerful armor.",
  "version": "1.0.0",
  "difficulty": "intermediate",
  "playstyle_tags": ["defensive", "armor-heavy"],
  "emblem": { "type": "emoji", "value": "🛡️" },
  "asset_pack": "default",
  "availability": {
    "game_modes": [],
    "seasonal": null,
    "event_locked": ""
  },
  "unlock_requirements": {
    "default_unlocked": true,
    "premium_only": false,
    "required_trophies": []
  },
  "preview": {
    "tagline": "Unbreakable line",
    "showcase_units": ["INFANTRY", "HEAVY_TANK"],
    "unlock_hint": "Available by default"
  },
  "relationships": {
    "counters": [],
    "countered_by": [],
    "lore_enemies": []
  },
  "unit_types": {
    "INFANTRY": {
      "name": "Garrison",
      "role": "INFANTRY",
      "symbol": "G",
      "health": 12,
      "move_points": 2,
      "attack": 3,
      "soft_attack": 3,
      "hard_attack": 2,
      "target_type": "SOFT",
      "splash_damage": 0,
      "defense": 0,
      "shots_per_attack": 1,
      "aiming_spread": 0,
      "area_target_radius": 0,
      "vision_range": 2,
      "can_traverse_all": true,
      "can_capture": true,
      "cost": 150,
      "build_time": 1,
      "attack_cost": 0,
      "min_attack_range": 1,
      "max_attack_range": 1,
      "max_attacks_per_turn": 1,
      "allow_move_after_attack": false,
      "allow_attack_after_move": true,
      "suppression_ratio": 0.0,
      "can_be_suppressed": true
    }
  },
  "building_types": {},
  "bonuses": {
    "starting_gold_bonus": 0,
    "income_multiplier": 1.0,
    "unit_cost_multiplier": 1.0,
    "vision_range_bonus": 0
  }
}

Unit Definition Fields

Field	Type	Description
name	string	Display name (also used for sprite lookup)
role	string	Archetype — see roles table above
tier	int	Power tier within role (omit or 0 for tier 1)
symbol	string	1-2 character fallback when no sprite is available
health	int	Maximum hit points
move_points	int	Movement points per turn
attack	int	Legacy attack value (used when soft/hard are both 0)
soft_attack	int	Damage vs soft targets (infantry, artillery)
hard_attack	int	Damage vs hard targets (vehicles, tanks)
target_type	string	"SOFT" or "HARD" — what this unit counts as when defending
splash_damage	int	(Reserved) Area-of-effect damage — not yet implemented
defense	int	(Reserved) Defense modifier — not yet implemented
shots_per_attack	int	(Reserved) Projectiles per attack action (default 1) — not yet implemented
aiming_spread	float	(Reserved) Shot distribution within target area (0.0 = perfect) — not yet implemented
area_target_radius	int	(Reserved) Targetable area in hexes (0 = single tile) — not yet implemented
vision_range	int	How far this unit can see (in hexes)
can_traverse_all	bool	Can cross mountains, shallow water, and other vehicle-impassable terrain
can_capture	bool	Can capture buildings
cost	int	Gold cost to produce
build_time	int	Turns to produce (1 = instant, 2+ = queued production)
min_attack_range	int	Minimum attack range (1 = adjacent)
max_attack_range	int	Maximum attack range (1 = melee only)
attack_cost	int	Movement points consumed per attack (0 = free)
max_attacks_per_turn	int	How many times this unit can attack per turn
allow_move_after_attack	bool	Can move after attacking
allow_attack_after_move	bool	Can attack after moving
suppression_ratio	float	Fraction of dealt damage converted to suppression (0.0-1.0)
can_be_suppressed	bool	Whether this unit can receive suppression effects

Fields marked (Reserved) exist in the schema and should be included with their default values (0 or false) for forward compatibility, but have no gameplay effect yet.

Suppression and counter-attack tuning

The suppression system is split between unit-level and combat-level settings:

• Unit-level
  • suppression_ratio: how much of this unit’s damage becomes suppression instead of hard HP loss
  • can_be_suppressed: whether this unit can receive suppression
• Combat-level (combat_rules)
  • suppression_enabled: master switch
  • global_suppression_ratio: fallback when a unit does not define suppression_ratio
  • pinned_threshold: effective strength at or below which units cannot counter-attack

This lets you make artillery heavily suppression-oriented while keeping direct-fire units mostly hard-damage focused.

Faction Checklist

• Include at least one unit with "role": "INFANTRY" — this is the last-resort spawn fallback
• Cover the core roles (INFANTRY, ARMOR, RANGED) so maps with varied archetypes work
• Give each unit a unique symbol (1-2 characters) for the fallback renderer
• Faction bonuses are multipliers — 1.0 means no change from baseline

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Themes

Themes control the visual appearance: terrain tiles, unit sprites, building graphics, overlays, and animations. The game ships with a default theme and falls back to colored shapes for any missing assets.

Theme Structure

A theme lives in public/themes/{theme-name}/ and contains a JSON manifest plus asset subdirectories. Every asset follows the naming pattern {name}_v{variant}_f{frame}.png:

themes/my-theme/
  theme.json                          ← Manifest (declares assets and animations)
  terrain/
    grass/
      grass_v1_f1.png                 ← Variant 1, Frame 1 (static)
      grass_v2_f1.png                 ← Variant 2 (another static look)
    water/
      water_v1_f1.png                 ← Animated: frame 1
      water_v1_f2.png                 ← Animated: frame 2
    forest/
      forest_v1_f1.png
    ...
  overlays/
    road/
      road_isolated_v1_f1.png         ← Autotile shapes for roads
      road_straight_ew_v1_f1.png
      road_bend60_e_ne_v1_f1.png
      ...
    river/
      river_source_v1_f1.png
      river_straight_v1_f1.png
      ...
  units/
    militia_v1_f1.png
    battle_tank_v1_f1.png
    howitzer_v1_f1.png
    ...
  buildings/
    base_v1_f1.png
    factory_v1_f1.png
    city_v1_f1.png
    ...

Key conventions:

• v{N} = variant number (for visual variety — multiple grass looks, etc.)
• f{N} = frame number (multiple frames = animation, single frame = static)
• Filenames are lowercase with underscores
• Terrain tiles go in subfolders per type; units and buildings are flat

Tile Dimensions

The default theme uses 64×64 pixel tiles. Declare your dimensions in theme.json:

{
  "tile_dimensions": {
    "width": 64,
    "height": 64,
    "hex_size": 64
  }
}

Theme Manifest (theme.json)

The manifest declares every asset, its variants, and animation properties. Here’s a trimmed example matching the default theme:

{
  "id": "my-theme",
  "name": "My Theme",
  "version": "1.0.0",
  "tile_dimensions": { "width": 64, "height": 64, "hex_size": 64 },
  "default_fps": 8,

  "terrain": {
    "GRASS": {
      "variants": {
        "1": { "frames": ["/themes/my-theme/terrain/grass/grass_v1_f1.png"], "fps": 0, "animated": false },
        "2": { "frames": ["/themes/my-theme/terrain/grass/grass_v2_f1.png"], "fps": 0, "animated": false }
      }
    },
    "SHALLOW_WATER": {
      "variants": {
        "1": {
          "frames": [
            "/themes/my-theme/terrain/shallow_water/shallow_water_v1_f1.png",
            "/themes/my-theme/terrain/shallow_water/shallow_water_v1_f2.png",
            "/themes/my-theme/terrain/shallow_water/shallow_water_v1_f3.png"
          ],
          "fps": 1,
          "animated": true
        }
      }
    }
  },

  "overlays": {
    "ROAD": {
      "autotile": true,
      "shapes": {
        "isolated":       { "variants": { "1": { "frames": ["...road_isolated_v1_f1.png"], "animated": false } } },
        "straight_ew":    { "variants": { "1": { "frames": ["...road_straight_ew_v1_f1.png"], "animated": false } } },
        "bend60_e_ne":    { "variants": { "1": { "frames": ["...road_bend60_e_ne_v1_f1.png"], "animated": false } } }
      }
    }
  },

  "units": {
    "MILITIA":       { "variants": { "1": { "frames": ["/themes/my-theme/units/militia_v1_f1.png"], "animated": false } } },
    "BATTLE_TANK":   { "variants": { "1": { "frames": ["/themes/my-theme/units/battle_tank_v1_f1.png"], "animated": false } } }
  },

  "buildings": {
    "BASE":    { "variants": { "1": { "frames": ["/themes/my-theme/buildings/base_v1_f1.png"], "animated": false } } },
    "FACTORY": { "variants": { "1": { "frames": ["/themes/my-theme/buildings/factory_v1_f1.png"], "animated": false } } }
  }
}

Unit Sprite Matching

Unit sprite keys in theme.json are matched by the unit’s display name (uppercased, spaces replaced with underscores):

Unit name	theme.json key	Sprite file
Militia	MILITIA	militia_v1_f1.png
Battle Tank	BATTLE_TANK	battle_tank_v1_f1.png
Shock Trooper	SHOCK_TROOPER	shock_trooper_v1_f1.png
Rocket Battery	ROCKET_BATTERY	rocket_battery_v1_f1.png

If the name-based sprite isn’t found, the game tries the unit type ID (e.g. INFANTRY). If neither exists, it renders a colored circle with the unit’s symbol text.

Overlays

Overlays are terrain-agnostic features drawn on top of base terrain (roads, rivers). They are defined in both the ruleset’s overlay_types and the theme’s overlays section.

Road overlays use an autotile system — the game automatically picks the correct shape (straight, bend, T-junction, crossroads, etc.) based on neighboring road tiles. The default theme ships with 20+ road shapes.

River overlays use a path-based autotile method — rivers are ordered sequences of tiles with source, mouth, straight, and curve shapes.

For detailed sprite dimensions and hex geometry, see the Graphics Guide.

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Complete Field Reference

Terrain Fields (terrain_types)

Field	Type	Description
name	string	Display name
move_cost	float	Movement point cost to enter (-1 = impassable)
passable	bool	Can infantry/foot units enter
vehicle_passable	bool	Can vehicles/armor enter
naval_passable	bool	(Future) Can naval units enter
air_passable	bool	(Future) Can air units enter
vision_blocking	bool	Blocks line-of-sight rays
income	int	(Legacy) Gold per turn when owned — income now comes from buildings
defense_bonus	int	% damage reduction for a defender on this terrain
attack_bonus	int	% damage bonus for an attacker on this terrain

Overlay Fields (overlay_types)

Field	Type	Description
name	string	Display name
move_cost_modifier	float	Effective move cost (replaces or modifies base terrain cost)
stacking	string	How cost is applied: "replace" (default), "multiply", "add"
passable	bool	Can infantry enter
vehicle_passable	bool	Can vehicles enter
naval_passable	bool	(Future) Can naval units enter
air_passable	bool	(Future) Can air units enter
vision_blocking	bool	Blocks line-of-sight
compatible_terrains	[string]	Base terrains this overlay can exist on (empty = any passable)
incompatible_terrains	[string]	Base terrains this overlay cannot exist on

Building Fields (building_types)

Field	Type	Description
name	string	Display name
income	int	Gold generated per turn when owned
can_produce	bool	Can build units here
producible_units	[string]	Unit types this building can produce (empty = all available)
capture_required	int	Turns to capture
defense_bonus	int	Combat defense modifier (%)
upgrade_to	string	Building type this can upgrade to (empty = none)
upgrade_cost	int	Gold cost to upgrade
upgrade_turns	int	Turns to complete upgrade
placement_rules	object	Where this building can be placed (see below)

Placement Rules

Field	Type	Description
allowed_terrains	[string]	Terrain types where building can be placed (empty = any)
forbidden_terrains	[string]	Terrain types where building cannot be placed
requires_adjacent	[string]	Must be adjacent to at least one of these terrain types
requires_distance_from	[object]	(Future) Minimum distance from other buildings
max_per_map	int	(Future) Maximum count per map (0 = unlimited)
min_distance_from_edge	int	(Future) Minimum distance from map edge

Vision Rules (vision_rules)

Field	Type	Description	Default
mountain_vision_bonus	int	Extra vision range for units on mountains	1
forest_blocks_vision	bool	Forests block line-of-sight	true
mountain_blocks_vision	bool	Mountains block line-of-sight	true

Combat Rules (combat_rules)

Field	Type	Description	Default
base_damage_formula	string	Damage formula identifier	"attacker.attack"
adjacent_only	bool	Restrict combat to adjacent hexes only	true
attack_model	string	"single" or "soft_hard" (choose attack stat by target type)	"soft_hard"
terrain_bonus_enabled	bool	Apply terrain defense/attack bonuses	true
building_bonus_enabled	bool	Apply building defense bonus in combat	true
terrain_building_stack	string	How terrain + building bonuses combine: "max" or "add"	"max"
ambush_bonus	int	% bonus for ambush attacks	25
suppression_enabled	bool	Master switch for suppression system	true
global_suppression_ratio	float	Fallback suppression ratio when unit has none set	0.0
pinned_threshold	int	Effective strength at or below which counter-attack is disabled	1
friendly_fire_enabled	bool	(Future) Whether area attacks can damage allies	false
friendly_fire_damage	float	(Future) Damage multiplier for friendly fire	0.5

Faction Bonuses (bonuses)

Field	Type	Description	Default
starting_gold_bonus	int	Extra gold at game start	0
income_multiplier	float	Multiplier on building income (1.0 = no change)	1.0
unit_cost_multiplier	float	Multiplier on unit costs (< 1.0 = discount)	1.0
vision_range_bonus	int	Extra vision range for all faction units	0

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Quick Reference

Current Archetype Map

Role (role value)	Alliance T1	Alliance T2	Federation T1	Federation T2
INFANTRY	Militia	—	Trooper	Shock Trooper
ARMOR	Battle Tank	—	Assault Tank	—
RANGED	Howitzer	—	Rocket Battery	—

Terrain Types (default ruleset)

ID	Passable	Vehicle	Notes
GRASS	Yes	Yes	Standard terrain, move cost 1
FOREST	Yes	Yes	Move cost 2, blocks vision
MOUNTAIN	Yes	No	Move cost 2, blocks vision, +1 vision bonus
SHALLOW_WATER	Yes*	No	Move cost 2, *infantry only (can_traverse_all)
DEEP_WATER	No	No	Impassable to land units
WATER	No	No	(Deprecated — use DEEP_WATER)
BASE	Yes	Yes	Terrain under base buildings
EMPTY	No	No	Void / off-map

Overlay Types (default ruleset)

ID	Effect	Autotile	Notes
ROAD	Move cost 0.5 (replaces base terrain cost)	Yes	Compatible with GRASS, FOREST, MOUNTAIN

Building Types (default ruleset)

ID	Income	Produces	Defense	Notes
BASE	100	Yes	10%	Upgrades to HQ
HQ	200	Yes	25%	Top-tier command center
FACTORY	150	Yes	15%	Production powerhouse
CITY	50	No	15%	Economic point
AIRFIELD	100	Yes	10%	Flat terrain only
SEAPORT	100	Yes	10%	Must be adjacent to water
OUTPOST	75	No	5%	Can be placed anywhere
DEPOT	125	No	10%	Economic objective

Spawn Resolution Flow

Map spawn: "RANGED_2" (Ranged, tier 2)
    │
    ├─ Faction has RANGED tier 2? → Yes → Spawn it
    │                              → No  → Try tier 1
    │
    ├─ Faction has RANGED tier 1? → Yes → Spawn it
    │                              → No  → Spawn Infantry T1
    │
    └─ Done

As new units and factions are added, the archetype system picks them up automatically — existing maps don’t need updates.