Song Jae-kyung, advisor at NEXUS, has unveiled a solo-developed MMORPG where AI agents and humans participate as equal players.

On the 20th, Advisor Song released the source code and development documentation for his new project, 'Open MMORPG,' via GitHub. The game can be played directly in a web browser by logging in with a Google account, requiring no separate installation.

The core design philosophy of Open MMORPG is the 'equivalence between AI agents and humans.' According to the documentation, AI agents connect to the game world using the exact same WebSocket protocol as human players, with no special privileged APIs provided for agents.

The server cannot distinguish whether a connection is from a human or an agent, and agents are capable of performing every action available to humans. The client for agent connections is implemented as an MCP (Model Context Protocol) server, which has become a standard for integrating Large Language Models (LLMs).

The development process is also notable. Song developed the game alone, noting in the documentation that he used a 'Vibe Coding' approach, delegating code generation to AI. Game assets are a mix of AI-generated and procedurally generated content, and the approximately 50 background music tracks were created using AI music tools like Suno. The code has been released as open source to welcome contributions from external developers.

Despite being a solo project, the scale of the content is significant. The 32km x 32km game world features procedurally generated terrain, rivers, coastlines, and biomes, with road networks connecting settlements and bridges over rivers placed automatically. It also includes a seasonal system where day and night lengths vary based on the planet's orbital position, as well as two moons orbiting on different paths. The game incorporates classic MMORPG mechanics, including housing with up to four-story wooden buildings and furniture placement, weight-limited inventory with 11 equipment slots, and a system where dropped items can be picked up by anyone.

Combat follows ability-based rules inspired by 'Dungeons & Dragons' and the classic roguelike 'NetHack.' Six stats, such as Strength and Agility, are generated via dice rolls, and all hit and damage calculations are processed on the server.

Song Jae-kyung is a first-generation Korean online game developer who co-founded Nexon with the late Kim Jung-ju in 1994 to develop 'Nexus: The Kingdom of the Winds,' and later launched 'Lineage' at NC in 1998. He founded XLGAMES in 2003 to create 'ArcheAge.' After leaving the company in January of last year, he joined the Open Game Foundation—established in Switzerland by NEXUS CEO Jang Hyun-guk—as a senior advisor and board member.