Save System Architecture

Status: RESOLVED — July 19, 2026

---

Save Types

1. Run State (Mid-Run Save)

• Single slot. One save file per run. Overwrites on save. Deleted on victory or defeat.
• Autosave at each node start and end.
• Manual "Save & Quit" available from pause menu.
• No save-scumming: saving mid-battle is not possible (only between nodes).

2. Meta-Progression (Persistent)

• Echoes balance, unlocks purchased, run history, bestiary, synergy codex.
• Saved as JSON file in persistent data path.
• Steam Cloud Saves for cross-device sync (post-MVP: v1.0).

3. Settings (Persistent)

• Audio, video, controls, accessibility. Unity PlayerPrefs or JSON.

---

Serialization Format

• System.Text.Json for run-state and meta-progression saves.
• Definitions (aspects, enemies, relics) are ScriptableObjects — referenced by ID in save files, not serialized inline.

Save Payload (Run State)

RunSaveData
├── version: int
├── seed: int
├── difficulty: enum
├── islandIndex: int
├── currentNodeIndex: int
├── nodeHistory[]: List<NodeResult>
├── squad: SquadData
│   ├── units[]: List<UnitSaveData>
│   │   ├── unitId, characterId, level, exp
│   │   ├── aspectSlots[5]: string[]  // aspect IDs
│   │   ├── abilityUpgrades: dict<string, int>  // ability ID → tier
│   │   ├── equipment: EquipmentSlots
│   │   ├── stats: StatBlock
│   │   └── hp, mp
│   └── inventory: InventoryData
├── relics[]: List<string>  // relic IDs
├── gold: int
├── synergiesDiscovered[]: List<string>
├── playTime: float
└── isCoop: bool

---

Save Triggers

Trigger	What Saves
Node start	Autosave run state
Node end	Autosave run state
Manual "Save & Quit"	Full run state
Victory	Save final stats, award Echoes, delete run save
Defeat	Save final stats, award Echoes, delete run save
Game close (graceful)	Autosave if mid-run
Game crash	Nothing. Risk accepted.

---

Co-op Saves

• Host owns the save. Co-op runs cannot be resumed if host disconnects.
• No reconnection support for MVP. Disconnect = run lost for both.
• Consider "Save & Quit" for co-op (both players confirm) in v0.2.

---

Open Questions

• [ ] Save file versioning: migration strategy for v0.1 → v0.2 saves?
• [ ] Encryption: probably skip (not a competitive game).
• [ ] Dev tools: spawn items, skip islands, set Echoes via console commands?