Epic Games took a big step with conversational AI when it added a new version of Darth Vader in Fortnite that could speak with players. But later this year, any creator using Unreal Editor for Fortnite (UEFN) will be able to make their own AI-powered characters with the same underlying technology behind Vader.
During the 2025 State of Unreal keynote, Epic revealed that a new tool in UEFN called the Persona Device will allow anyone to create non-playable characters (NPCs) with AI-driven personalities. The company showed this in action with an internal demo where the player has to talk to a robot named Mr. Buttons. Epic Games executive vice president Saxs Persson said this was meant to show how the Persona Device can “enable emergent, reactive gameplay for creators and deeper experiences for players.”
Within the demo’s Verse code (the programming language used in UEFN), the AI prompt that defines Mr. Buttons’ personality describes it as a “mysterious cosmic entity” with infinite knowledge and curiosity, and that it must respond to the player with “comedic finesse.” Mr. Buttons appears as a floating metal sphere with a glowing eye, and it has one singular purpose: to get you to press the big red button at the center of a catwalk.
You don’t know what will happen if you press the button, and if you ask Mr. Buttons about it, it’ll give you vague but playful answers. If you comply with the robot’s request, the screen darkens, and the demo is immediately over. But as with the AI Darth Vader, you can try steer the conversation into other topics or even probe deeply into why it wants you to push the button so badly. It uses filler words like “ums” and “ahs” while it generates an answer to your questions.
Epic hasn’t said whether this tech demo will be released publicly through Fortnite. But I was able to try it for myself while I was in Orlando, FL to attend the keynote and the Unreal Fest conference. I actually tried it two separate times just to see how both experiences would compare.
It was hard not to think about the Portal series while I played — Mr. Buttons’ personality seemed clearly inspired by the sarcastic robots in Valve’s mind-bending puzzle games. But in this case, Mr. Buttons isn’t following a script written by a team of writers, nor is its voice coming from a real actor. So its jokes and comments can never live up to the likes of GLaDOS or Wheatley from Portal.
That said, I was surprised with the way Mr. Buttons could tease me and remember things we discussed earlier in our conversation. In my first playthrough, I asked it to tell me about the button and why it was so important, and it responded with short stories about the button’s role through time and space. Mr. Buttons also kept promising to reward me with vast amounts of pizza if I followed its orders.
The second time around I tried being a little more creative. At one point, I asked Mr. Buttons about its childhood, and it said, “My childhood? Oh, darling, it was an explosion of cosmic dust and infinite possibilities! Imagine nebulas for playgrounds and supernovae for birthday candles. Quite the spectacle.”
I also told it to only speak to me through rhymes, and later, as if it was in a Shakespeare play. “Hark, what light through yonder button breaks? It is the east, and pushing it awakes a slumbering giant for goodness sakes. Now press it ere the cosmos aches,” Mr. Buttons said.
It was a very superficial imitation, but it wasn’t too far off from similar prompts I’ve given to ChatGPT and other text-based generative AI tools. And it does sound funnier when you hear an AI say those things out loud with varying levels of intonation. Like with the stage demo, there were still moments of awkward pronunciations and phrases, along with some repetition (it kept prefacing its answers with “Ah, a question for the ages” to me).
What makes the Persona Device different from AI Darth Vader is that developers can use these NPCs to affect the state of the world in their UEFN games. Mr. Buttons, for example, wouldn’t let you leave the room — if you tried to open the door, you’d simply return to the catwalk and see a visibly angry robot (now with a red eye) looking back at you. But these actions have to be deliberately programmed within the game since the AI can’t generate new assets or interactions out of nothing.
Overall, the Mr. Buttons tech demo was an amusing example of what kind of games developers can create with these AI NPCs. But I’m not sure about how long they’d be able to keep players entertained. I could’ve kept talking to Mr. Buttons as long as I wanted to, but in both of my demo sessions, I lost interest after just a few minutes. I’m curious to see how these characters hold up in a larger game filled with other objectives and mechanics.
It’s also hard not to think about the risks of unleashing conversational AI into these worlds, especially when big intellectual property is involved. Despite the safeguards that Epic built in for AI Darth Vader, players were still able to trick it into swearing and saying other problematic phrases. In response, Epic quickly issued an update that it said would prevent future incidents.
SAG-AFTRA, the major union for actors, also took issue with the character and how it uses the voice of late actor James Earl Jones, who portrayed Darth Vader in Star Wars media (Epic trained the AI on Jones’ own voice with the blessing of his family). It’s unclear what sort of voices creators will have access to in UEFN.
I don’t think I’d ever play a game completely focused on AI-powered NPCs, especially if it’s meant to be more story-driven. But I can see the value for smaller teams in using a tool like this to create novel experiences, or to add some variety in their games. It’ll ultimately be up to the creators to determine how useful the Persona Device will be.
Disclosure: Epic Games paid my way to Unreal Fest.
