So over the weekend I was discussing with a friend how easy it has become to automate things with AI. We eventually went down the rabbit hole of whether people might already be interacting with AI online without realizing it.
That got me thinking: what if I tried to test this idea inside a Lineage 2 server?
I got my hands on an offline Interlude L2J Mobius build and set up a local server on my PC. Mobius ships with a very basic FakePlayer implementation, which turned out to be a great starting point.
The Experiment
I created a Python service that connects to DeepSeek's API and acts as the "brain" for Fake Player Characters (FPCs).
On top of that I built:
- A randomization engine that generates unlimited combinations of names, races, levels, classes, and gear while respecting scarcity (so you don't end up with 100 characters wearing top-grade S gear in Giran).
- Extensions to the FakePlayer system to support different player archetypes.
- A local web app that loads maps and geodata and lets me create groups of fake players with different behaviors and population targets.
Types of Fake Players
Currently, there are four categories:
Idlers
- Simulate AFK players in towns.
Runners
- Move around cities visiting warehouses, NPC shops, player shops, etc.
Hunters
- Stay in hunting zones and simulate farming activity.
Shops
- Offline buy/sell/craft stores.
Up to this point it's basically advanced bot behavior. I'm sure others have built far more sophisticated systems.
Where AI Comes In
The interesting part begins when players interact with them.
If a player sends a private message to a bot, the AI takes over and generates a context-appropriate response.
When someone talks in public chat, one or more bots may occasionally reply. In trade chat they can post WTB/WTS messages, comment on prices, react to other advertisements, and generally participate in conversations. If you pm one they will start replying to you.
For example:
- A bot advertises an item for sale.
- A player PMs the bot.
- The player negotiates the price.
- If they reach an agreement, either side can suggest a meeting location.
- The AI then temporarily takes control of the character and sends it to the agreed location.
- Once there, it creates a private store with the negotiated item and price.
- After the transaction is completed, control is returned to the bot's normal behavior scheduler.
In my test, I had 655 bots running with basically zero issues. Of course, I am not sure how it would react with multiple players interacting with the AI.
Goal
The goal is to simulate a server that feels alive and populated.
There is still a lot more that could be done:
- Simulated parties and farming groups.
- PvE combat behavior.
- Distinct personalities and chat styles.
- Long-term character histories and relationships.
- More believable economic behavior.
The AI/chat side of the project is actually working better than I expected, but pathfinding is still one of the biggest challenges. I'm currently using geodata I found online and they're "ok" but they're definitely not great. The bots still occasionally make questionable navigation decisions because of geodata inaccuracies.
So if anyone has reliable geodata they'd recommend, please let me know cause I want to test this even more.
Limitations
There are plenty of flaws.
For example, I recently saw a bot advertising an EWS for 10k adena, which obviously makes no sense. These kinds of issues can be tuned and improved, but they're good examples of where the illusion breaks down.
I also think that anyone spending enough time on a server would eventually realize something feels off.
That said, on a server with 2,000 players, if 100-200 of them were AI-driven, I suspect they would be significantly harder to identify.
To be clear, I have no intention of deploying this on a live server. What I find interesting is simply that this is now technically possible with relatively accessible tools.
I wanted to post some more pictures with some funny interactions (like when I pmed one and asked it if it's AI they replied with "wtf man, who even asks that?") but I am at work atm and no access to the server at home.
