A modern game needs:

• reliable save/load systems
• world state persistence
• player progression
• inventory & quests
• NPCs and simulation state
• safe serialization & versioning
• replay systems
• modding and content pipelines

Lua is ideal for all of this:

• tables serialize well
• code is data, data is code
• tables are readable and versionable
• hot reload simplifies pipelines
• modding = just load more Lua files

This chapter builds a complete system that scales from small to AAA-style persistence.

Modern online games need to store huge amounts of data: player accounts, inventory, currencies, stats, world progress, guild data, match results, analytics—the list is endless.
Unlike single-player games, nothing can be saved locally on the player’s device because it can be modified, hacked, or lost.

This chapter introduces the fundamentals of persistence for game servers, including:

• Player data modeling
• Inventory & economy systems
• Saving and loading data
• Databases for games
• Event-driven persistence
• Preventing lost progress
• Scaling to millions of players

Persistence is one of the most important aspects of running an online game reliably and safely.