Battle System Design

Source: Extracted and expanded from master_gdd.md §3.
Status: DRAFT — needs producer review on numeric parameters.

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Table of Contents

1. The Grid
2. Turn Order — The CT Timeline
3. Damage — Deterministic
4. Height Mechanics
5. Core Verbs
6. Downed State & Permadeath
7. Status Effects
8. UI & Feedback
9. Scope Boundaries
10. Open Questions

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1. The Grid

Dimensions

• 8 columns × 12 rows (portrait orientation)
• Isometric rendering — rows are offset for diamond-tile illusion
• Wider at top with perspective projection for depth

Height Tiers

Tier	Value	Examples	Gameplay Impact
Pit	−1	Water, lava, void, chasm	Cannot walk. Fly/teleport only. Fall into = banished at height 0.
Ground	0	Grass, stone, ash, marble	Default. All units can traverse.
Platform	+1	Crates, low walls, shallow hills	Step up costs +1 move. Small advantage.
Elevated	+2	Cliffs, buildings, pillars	Step up costs +2 move. Significant advantage.
Tower/Peak	+3	Watchtowers, floating platforms, caldera rim	Step up costs +3 move. Major LOS and damage advantage.

Tile Properties

Each tile can hold:

• Height (int, −1..+3)
• Terrain type (determines visuals, footstep SFX, and elemental interactions)
• Hazard (null or a timed/damage effect: lava, poison cloud, electrified water)
• Cover (null or a destructible obstacle with HP)
• Occupant (null or one unit)
• Prepared effect (Ritualist-trapped tiles, Engineer mines)

Deployment Zones

Battle Type	Player Deploy	Enemy Deploy
Standard	Left 2 columns (x=0,1), any y, ground height	Right 2 columns (x=6,7), any y, ground height
Ambush	Center 4×4 square	Perimeter: all tiles at distance ≥ 4 from center
Escort	Left 2 columns + NPC at (x=2, y=6)	Right 2 columns + reinforcement spawns
King of the Hill	Edge columns (x=0,7)	Edge columns (opposite side)
Boss	Map-specific	Pre-placed, hand-authored

Camera

• Isometric fixed angle (30° or 45°?)
• Player can pan (scroll edges or middle-mouse drag)
• Zoom range: can see entire grid at minimum zoom, ~4×6 tiles at maximum
• Co-op: each player has independent camera

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2. Turn Order — The CT Timeline

CT Formula

CT_this_tick = CT_previous + Speed
If CT ≥ 100: unit is READY to act
After acting: CT -= 100 (overflow carries to next cycle)

Speed Values (Design Range)

Speed	Description	Example Unit
1–4	Very slow	Golem, heavily armored Knight
5–7	Slow	Knight, Priest, Mage
8–10	Moderate	Archer, Shaman, Bard
11–14	Fast	Rogue, Monk, Beastmaster
15–18	Very fast	Hasted unit, Ninja-equivalent
19–20	Capped maximum	Chronomancer-buffed, boss phase

Tick Resolution

• Ticks are discrete. No fractions.
• Multiple units reaching CT ≥ 100 on the same tick: player units act first (choose order), then enemies (AI decides order).
• Co-op: P1 → P2 on the same tick (whichever player's units hit CT first).

The Timeline Bar (UI)

 ┌──────────────────────────────────────────────────────────────┐
 │ TICK:    1      2      3      4      5      6      7      8  │
 │        [You]          [EnemyA]    [Ally]      [EnemyB]    [You]
 │        Slash          Fireball    Heal@       Bite        ???
 │        @(3,4)         lands(6,2)  (3,3)       @(5,4)
 │                        ⚠ CANCEL?                            │
 └──────────────────────────────────────────────────────────────┘

Display requirements:

• Always visible (bottom or top of screen)
• Current tick highlighted
• Player's upcoming actions clearly marked
• Enemy actions show: ability name, target tile, damage number
• Charge spells show countdown: [⏳ 2 turns remaining]
• Cancellable spells show ⚠ CANCEL? badge
• Hover over any entry shows tooltip with full details

Speed Manipulation

Effect	CT Impact	Timeline Display
Haste	Target gains +50% Speed for 3 ticks	Unit icon slides LEFT on timeline
Slow	Target loses −50% Speed for 3 ticks	Unit icon slides RIGHT on timeline
Stop	Target's CT freezes for 2 ticks	Unit icon freezes, shows 🔒
Rewind	Target's CT set to 0	Unit jumps to back of queue
Encore	Ally acts again immediately	Extra turn inserted at current tick

Charge Time & Cancellation

Spells with charge time:

1. Caster begins casting at their turn. Spell enters timeline at tick N + charge_time.
2. If caster takes any damage during charge: spell cancelled. ⚠ CANCEL? appears on timeline.
3. If caster is displaced (pushed/pulled/teleported): spell cancelled.
4. If caster is killed/downed: spell cancelled.
5. If caster is stunned/stopped/frozen: spell cancelled.
6. If target tile is raised/lowered (terrain change): spell hits new height. Can result in miss if target is no longer there.

Cancellation Hierarchy

What Happens	Does Spell Cancel?
Caster takes damage	Yes
Caster pushed/pulled	Yes
Caster teleported (ally)	Yes
Caster stunned/stopped/frozen	Yes
Caster killed/downed	Yes
Target moves out of AoE	No — spell hits the tile, even if empty
Target dies before spell lands	No — spell hits the tile (may hit corpse for some effects)
Cover placed in spell path	Spell hits the cover (cover takes damage)
Spell timer expires normally	Spell resolves, hits tile

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3. Damage — Deterministic

Base Formula

Damage = Ability_Base_Damage − Target_DEF
Minimum damage = 1 (unless absorbed/voided entirely)

No variance. No crits. No miss chance (except Evasion defense aspect — see below).

Damage Types

Type	Used By	Defended By	Special
Physical	Strike, Shoot, Shove into wall	DEF	Standard
Magical	Cast, elemental spells	DEF (magic) or Ward	Can have elemental tags
True	Fall damage, %HP effects, poison	None	Ignores all DEF/resistances
Heal	Heal abilities	None (negative damage)	Caps at max HP unless overheal

Elemental Interactions

Element	Strong vs.	Weak vs.	Terrain Interaction
Fire	Ice armor (+2 dmg)	Water armor (−2 dmg)	Ignites oil, evaporates shallow water
Ice	Fire armor (+2 dmg)	Ice armor (−2 dmg, immune)	Freezes water tiles (creates walkable surface)
Lightning	Water armor (+2 dmg), Wet status	Stone armor (−2 dmg)	Electrifies water (damage/tick to all in water)
Earth	Flying units (+2 dmg)	Air armor (−2 dmg)	Creates temporary cover, raises/lowers terrain
Wind	Earth armor (+2 dmg)	Stone armor (−2 dmg)	Pushes units, extends fall trajectories
Holy	Undead (+4 dmg)	Holy armor (−2 dmg)	Bonus vs Necromancer spawns
Dark	Living units (+2 dmg)	Dark armor (−2 dmg)	Damage scales with missing HP

The Evasion Exception

The Dodge Defense aspect (and certain enemy Tricksters) are the only non-deterministic mechanic. When a unit with Dodge is targeted:

• Timeline shows (?) instead of the damage number
• When the attack resolves, the dodge check happens
• The game never rolls dice for anything else

Justification: The Ninja fantasy requires the threat of unpredictability. The player can choose to target someone else and avoid the gamble entirely. The (?) telegraph means they know the risk before committing.

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4. Height Mechanics

Damage Modifier

Height Advantage = Attacker.z − Defender.z
Final Damage = Base_Damage × (1.0 + Height_Modifier)

ΔHeight	Range Mod	Damage Mod	LOS Rule
+3 or more	+2	+30%	Ignores LOS blockers ≤ attacker height
+2	+1	+20%	Normal LOS
+1	+1	+10%	Normal LOS
0	0	Normal	Normal LOS
−1	−1	−10%	Normal LOS
−2 or less	−1	−20%	Normal LOS

Fall Damage

Fall_Damage = (Height_Dropped × 3) true damage

• Push off a +3 ledge: 9 true damage
• Push off a +2 ledge: 6 true damage
• Into water/lava/void at height −1: banished (not dead — removed from battle, some bosses return)
• Unit with Flight movement aspect: immune to fall damage
• Unit with Stone Skin defense aspect: immune to push/pull (can't be shoved off)

Ranged Attacks Uphill

• Can only target tiles within base range + height range modifier
• Height difference may reduce effective range if shooting uphill
• Example: Archer at height 0 targeting +3: range −1 penalty applied
• Flying units attacking downward ignore range penalties

Terrain Manipulation

Verb	Effect	Target
Raise Terrain	Target tile's height +1 (max +3)	Any non-occupied tile
Lower Terrain	Target tile's height −1 (min −1)	Any non-occupied tile
Create Cover	Spawn destructible obstacle on target tile	Adjacent tile

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5. Core Verbs

Every unit can perform one Move and one Act per turn, in that order. Some abilities modify this (Haste grants an extra Move, Encore grants an extra Act).

Strike

Parameter	Value
Type	Physical, melee
Range	Adjacent (1 tile)
Base damage	Weapon-dependent (sword: 6–10, axe: 8–14, dagger: 3–5 × 2 hits)
Push	Some weapons push target 1 tile (if target not Stone Skin)
Height allowed	±1 height difference from attacker

Expanded parameters (TBD):

• [ ] Weapon-specific push distance (0, 1, or 2 tiles)?
• [ ] Strike from height advantage: bonus tile of push for every +2 height?
• [ ] Dual-wield (Rogue): two strikes, each at −2 damage?

Shoot

Parameter	Value
Type	Physical, ranged
Range	Weapon-dependent (bow: 3–5 tiles, crossbow: 2–4 tiles)
Base damage	Weapon-dependent (bow: 5–8, crossbow: 7–10)
LOS required	Yes (Bresenham raycast, blocked by cover)
Height penalty	−1 range per −1 height disadvantage

Expanded parameters (TBD):

• [ ] Ammo system? (Probably not for MVP — infinite arrows)
• [ ] Pin (Archer Key ability): immobilize target for 1 tick on hit?
• [ ] Volley (AoE): 3-tile line or 2×2 area?

Cast

Parameter	Value
Type	Magical, ranged
Range	Spell-dependent (2–6 tiles)
Charge time	0–3 ticks (instant spells = 0 charge)
Cancellable	Yes (see cancellation hierarchy)
LOS required	For targeted spells. Ground-targeted AoEs: no LOS required.

Charge time by spell tier (TBD):

Spell Tier	Charge Time	Example
Cantrip	0 ticks	Fire Spark, Frost Touch
Basic	1 tick	Fireball, Heal, Ice Lance
Advanced	2 ticks	Meteor, Holy Light, Tornado
Ultimate	3 ticks	Time Stop, Geomancy, Eclipse

Shove

Parameter	Value
Type	Physical, melee
Range	Adjacent
Push distance	1–3 tiles (aspect-dependent)
Into obstacle	Bonus damage = push distance × 2
Off ledge	Target takes fall damage
No damage on shove itself	Unless aspect modifier (Berserker: shove deals damage)

Grapple

Parameter	Value
Type	Physical, melee
Range	1–2 tiles
Pull distance	1–2 tiles toward user
Sets up combos	Pull into ally threat range, into hazard, off safe terrain
No damage	Unless aspect modifier

Fortify

Parameter	Value
Type	Self-buff
Effect	+DEF for 3 ticks, OR temporary HP shield, OR create cover on adjacent tile
Aspect-dependent	Knight: create cover. Berserker: temp HP. Priest: DEF buff.

Heal

Parameter	Value
Type	Magical, targeted
Range	Self or adjacent (Priest: range 1–3)
Charge time	0 ticks (instant)
Amount	MAG × 1.5 (TBD formula)
Overheal	Requires Healer's Wisdom aspect (excess → temp shield)

Taunt

Parameter	Value
Type	Status, targeted
Effect	Target enemy's next telegraphed action redirects to taunter
Duration	Until enemy acts once, or taunter dies
Immunity	Bosses partially resistant (50% chance to ignore taunt)

Teleport

Parameter	Value
Type	Movement-replace (replaces Move, not Act)
Range	2–4 tiles (aspect-dependent)
LOS	Not required
Height	Can teleport to any height
Ignores	Obstacles, hazards, occupied tiles
Some aspects	Blink: free action (doesn't consume Move). Shadowstep: must start/end in shadow.

Additional Verbs (expansion candidates)

Verb	Description	MVP?
Barrier	Create temporary HP wall on adjacent tiles	Post-MVP
Dispel	Remove buffs/debuffs from target	Yes (Priest)
Transmute	Change terrain type on target tile	Yes (Alchemist)
Deploy	Place turret/mine/trap (Engineer)	Yes
Pledge	Link two units (damage shared, buffs shared)	Post-MVP

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6. Downed State & Permadeath

State Machine

ALIVE → [HP reaches 0] → DOWNED → [counter expires] → DEAD
  ↑                         │          (permadeath for run)
  └── Revive ───────────────┘

Downed State

Property	Value
Can act?	No
Can move?	No
Can be targeted?	Yes (some enemies prioritize, some ignore)
Occupies tile?	Yes (blocks movement)
Counter duration	3 turns (shown as ⚰️3→⚰️2→⚰️1→💀)
Counter ticks	On the downed unit's would-be turn

Revive

Parameter	Value
Cost	1 action from any ally
Range	Adjacent (Priest: range 1–2)
HP after revive	25% of max HP
Counter reset?	Yes — counter stops, unit is ALIVE
Abilities granted?	Can act on their next turn (CT is reset to 0)

Permadeath Effects

When a unit dies permanently:

1. Their equipped Aspects are lost for the run (returned to inventory? TBD)
2. An empty slot opens in the squad
3. A "Last Will" note is generated and displayed (comedic tone)
4. Other units may have a brief banter reaction
5. Player can recruit a replacement at the next RECRUIT node

Co-op Ghost Mode

When one player loses all units:

1. That player enters Ghost Mode
2. Can still: ping, emote, spectate (free camera)
3. Cannot: take turns, control units
4. Surviving partner can revive one ghost-player unit at next CAMP if they have Phoenix Down
5. If both players lose all units → run over

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7. Status Effects

Buffs (Positive)

Status	Effect	Duration	Stackable?	Removable?
Haste	+50% Speed	3 ticks	No (refresh)	Yes (Dispel)
Fortified	+3 DEF	3 ticks	No (refresh)	Yes
Regen	Heal %HP per tick	3 ticks	No (refresh)	Yes
Shield	Absorb next hit	Until hit	No	Yes
Invisible	Cannot be targeted	2 ticks or until act	No	No
Flying	Ignore terrain, −accuracy vs you	Permanent (aspect)	N/A	N/A

Debuffs (Negative)

Status	Effect	Duration	Stackable?	Removable?
Slow	−50% Speed	3 ticks	No (refresh)	Yes (Cleanse)
Rooted	Cannot move (can act)	2 ticks	No	Yes
Frozen	Cannot move OR act	1 tick	No	Yes
Stunned	Cannot move OR act	1 tick	No	Yes
Poisoned	Take 2 true damage/tick	4 ticks	Yes (intensity)	Yes (Antidote)
Bleeding	Take 3 true damage/tick	3 ticks	Yes (intensity)	Yes (Heal)
Cursed	−3 ATK, −3 MAG	3 ticks	No	Yes (Dispel)
Burning	Take 1 damage/tick, can spread	3 ticks	No	Move to water
Wet	−50% fire damage, +50% lightning	3 ticks	No	Wait
Confused	Next action targets random unit	1 action	No	On hit

Interaction Table

Combo	Result
Wet + Lightning	×2 lightning damage, stun for 1 tick
Wet + Ice	Frozen for 2 ticks instead of 1
Burning + Oil tile	Explosion: 5 damage AoE, removes oil
Poisoned + Bleeding	Crimson Agony: both tick twice as fast
Invisible + Strike	Guaranteed crit (×1.5 damage)

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8. UI & Feedback

In-Battle HUD

Element	Location	Content
Timeline bar	Bottom of screen (horizontal scroll)	All tick entries, charge indicators
Unit info panel	Side (on hover/select)	HP, MP, stats, aspects, status effects
Action palette	Bottom-center (on unit select)	Available moves and acts
Targeting overlay	On grid	Move range, attack range, AoE shape, damage preview
Height indicator	On tile (hover)	Height tier color-code + number
Turn indicator	Top-center	"Your Turn" / "Player 2's Turn" / "Enemy Phase"
Undo button	Bottom-left	Last move only (not entire turn)

Feedback Priorities

Priority	Feedback	Method
Critical	Spell charge countdown	⏳ icon on timeline + target tile pulse
Critical	Unit about to permadie	Red flash on ⚰️ counter
High	Damage preview	Number overlay on target tile
High	Height advantage	+% damage text color-coded (green=advantage, red=disadvantage)
Medium	Synergy triggered	"Synergy Discovered!" popup with particle burst
Medium	Level-up available	Icon on unit portrait
Low	Ambience	Weather particles, tile glow for prepared effects

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9. Scope Boundaries

MVP (20–24 weeks)

• [x] Full CT timeline system with timeline bar UI
• [x] Full grid: 8×12, 5 height tiers, isometric rendering
• [x] All core verbs (Strike, Shoot, Cast, Shove, Grapple, Fortify, Heal, Taunt, Teleport, Deploy, Dispel, Transmute)
• [x] Downed state + permadeath + revive
• [x] Height mechanics (damage, range, LOS, fall damage)
• [x] Deterministic damage formula
• [x] Charge time + cancellation system
• [x] Status effects: Haste, Slow, Rooted, Frozen, Poisoned, Burning, Cursed
• [x] Single-move undo
• [x] Tooltip system

Post-MVP

• [ ] Additional status effects: Confused, Bleeding, Wet, Invisible
• [ ] Full undo (entire turn rewind, not just last move)
• [ ] Elemental interaction VFX (water electrification, oil fires)
• [ ] Kill-cam (cinematic replay of killing blow)
• [ ] Battle log (text history of all actions)
• [ ] Damage prediction accounting for all modifiers (currently: base damage − DEF only)

Won't Do (For Now)

• [ ] Facing mechanics (back attacks, flanking bonuses)
• [ ] Weapon durability
• [ ] Ammo system
• [ ] Cover-building as a free action
• [ ] Destructible terrain affecting pathfinding (post-collapse, grid updates)

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10. Open Questions

1. Tick resolution order: When multiple units hit CT ≥ 100 on the same tick, player units act first, but within player units, does the player choose order or is it Speed-descending? (Recommend: player chooses order for their units.)
2. CT cap: Is there a maximum CT value? If a unit is continuously Hasted and never acts, does CT overflow? (Recommend: cap at 200.)
3. Strike range from height: Can melee Strike hit a unit at +2 height? Current rule says ±1 height for melee. Should height advantage grant +1 melee reach? (Recommend: no — that's what ranged weapons are for.)
4. Spell charge damage threshold: "Any damage" cancels the spell. Should there be a minimum damage threshold? (Example: poison tick = 2 damage. Does this cancel the Archmage's Meteor?) (Recommend: yes, any damage. Poison is a valid counterplay to casters.)
5. Undo scope: Single-move undo is MVP. Full-turn undo? Post-MVP? What about undo in co-op? (Recommend: single-move undo in solo, no undo in co-op.)
6. Boss immunities: Which status effects can bosses resist? (Recommend: immune to Stun, Frozen, Confused; resistant to Slow/Rooted; vulnerable to everything else.)
7. Fall damage + death: If a unit at 3 HP is pushed off a +3 ledge (9 fall damage), do they go directly to Downed or is there a DEATH skip? (Recommend: Downed. Counter starts. Same as any HP→0 event.)

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Next: Aspect Catalog