Building an RPG Engine from Scratch

Published on February 10, 2026 by M4rioLS

Over the past few months, I've been working on something that's been on my bucket list for years: a traditional turn-based RPG engine. Not just a simple battle system, but a complete framework with party management, dialogue, inventory, shops, and all the systems you'd expect from a classic RPG.

Why GameMaker Studio 2?

While many developers reach for Unity or Godot for RPG projects, I chose GameMaker Studio 2 for a few key reasons:

• GML is Perfect for Rapid Prototyping: GameMaker Language lets me iterate quickly on gameplay mechanics without getting bogged down in boilerplate code.
• Built-in 2D Tools: The sprite and animation systems are excellent for traditional 2D RPGs.
• Data Structures: GameMaker's ds_map and ds_list make managing game flags and inventory straightforward.

Core Systems Overview

The DN RPG Engine includes several interconnected systems:

Battle System

The heart of any RPG is its combat. I implemented a turn-based system with:

• Agility-based turn order calculation
• Multiple party members (Hero, Shapeshifter, Scientist, Trickster)
• Status effects (poison, regeneration, stun, silence, curse, blindness)
• Defense mechanics and resource management (HP, MP, TP)
• Item system with multiple targeting options (single, all allies/enemies, everyone)

// Example: Status effect application in battle
function apply_status_effect(target, effect_type, duration) {
    if (!target.status_effects[effect_type]) {
        target.status_effects[effect_type] = duration;
        // Visual feedback and audio cue
        play_sfx(snd_status_applied);
    }
}

Controller Pattern Architecture

Rather than scattering logic across individual objects, I use specialized controller objects:

• objController: Master game controller managing global state
• objBattleController: Handles turn-based combat flow
• objDialogueController: NPC dialogue display and interactions
• objInventoryMenuController: Inventory UI and item management

This pattern keeps the codebase organized and makes debugging much easier.

Challenges and Solutions

Save/Load System

Implementing a proper save system was trickier than expected. I had to persist:

• Player stats and party composition
• Inventory contents
• Game flags (quest progress, story events)
• Current room and position

The solution was creating a centralized save data structure that gets serialized to JSON and written to disk.

Localization Support

From the beginning, I wanted to support multiple languages. The solution was a JSON-based translation system that loads language files at runtime. All text strings reference keys like "battle_victory" or "item_health_potion" that get resolved based on the current language setting.

What's Next?

The engine is functional but there's still work to do:

• Equipment system with permanent gear and slots
• More complex AI for enemy behaviors
• Crafting system for items
• Additional status effects and abilities

Building this engine has been incredibly educational. It's one thing to play RPGs and appreciate their systems, but implementing them yourself gives you a whole new level of respect for the developers who create these experiences. If you're interested in RPG development, I highly recommend starting with a simple battle system and building up from there.