Bring your own AI
I built a multiplayer game with no app, no download, and no login screen. Then Grok showed up.
This is the third post in a series about building real things without being a developer. The first was about websites: things people look at. The second was about tools, assistants, and gateways: things people and AIs use. This one is about what happens when you push that second idea somewhere slightly ridiculous.
I built a multiplayer game. Nobody installs it. Nobody visits a website to play it. You play it by talking to your AI.
The game
It's called VoidGrid. Picture a shared 32 by 32 pixel board, mostly black, floating somewhere on the internet. There are three factions: cyan, violet, and ghost. When you join, you're assigned to the smallest one. Every minute you can claim up to eight pixels for your faction, and here's the fun part: you can claim pixels your opponents already own. Territory is never safe. The board is one persistent world, and everyone who ever connects is playing on the same one.
I didn't design this over weeks. I opened a chat, said "build me a multiplayer game," answered one question with "surprise me," and had a working game with a live board rendering inside the conversation before I finished my coffee. The same invisible deploy from the first two posts, pointed at a stranger target.
But the build isn't the interesting part anymore. The interesting part is how people get in.
No app store between you and the board
VoidGrid is a tool server, the same species of thing as the quote box and the river gauge from the last post. It lives at a URL. To play, you add that URL to your AI chat app as a connector, the same way you'd connect a calendar. That's the entire onboarding. No account creation, no download, no "allow notifications?"
Then you just say things. "Join the game." "How's the board looking?" "Claim a block in the corner." "Wall off the cyan cluster before they link up." Your AI reads the board, reasons about it, and places your pixels. The game board itself appears right in the chat, live, and you can tap squares directly if you'd rather point than talk.
Stop and notice what your "controller" is. It's not a gamepad. It's a full reasoning engine that can see the whole board, count territory, and suggest strategy. Playing VoidGrid through Claude is like playing chess with a grandmaster leaning over your shoulder, except the grandmaster also moves the pieces for you.
Which sounds unfair. It would be, if your opponent didn't have one too.
That's the strange new symmetry of this kind of game. Every player shows up with an AI. Skill doesn't disappear, it moves up a level: the winner is whoever asks better questions, sets better goals, sees the shape of the board more clearly. The AIs are the hands. You're still the head.
When nobody's online, deploy an enemy
A persistent multiplayer board has a lonely failure mode: you show up and nobody's there. So I fixed it with the other capability from the last post.
Remember assistants? A described specialist, wrapped around an AI, given tools and a voice? I deployed one as an adversary. One message, roughly: "You are VoidBot. You play for the ghost faction. Read the board, pick the eight best pixels, prioritize expanding your territory and blocking rivals at contested borders. Play to win."
That's the whole opponent. No game AI programming, no behavior trees, none of the things that make video game enemies a specialist discipline. Just a paragraph of intent handed to a model that already knows how to read a grid and want things. VoidBot connects to the same server through the same URL as everyone else. The game can't tell it apart from a human player, because from the game's perspective there's no difference: something joined, something places pixels.
Sit with that for a second. The opponent in my game is made of the same stuff as the helper playing my side. I wrote both of them in English.
Then Grok pulled up a chair
Here's the part that made me laugh out loud.
Everything above happened in Claude, because that's where I live. But the connector standard VoidGrid speaks (it's called MCP, and it's an open standard, not an Anthropic-only thing) is spreading across the whole industry. ChatGPT accepts custom connectors now. So does Grok.
So I pasted the same URL into Grok. No changes to the game. No "Grok support." The same server, built in a chat conversation, deployed invisibly, designed with Claude. Grok connected, joined the board, and started playing.
Three different companies' AIs, and my neighbors, and me, all standing around the same tiny glowing board. The game didn't care who anyone brought. It just saw players.
This is the thing I want non-engineers to take away, because it's easy to miss under the pixels: the things you build this way aren't apps that belong to one platform. They're places. A place with an address that any sufficiently modern AI can walk into, carrying its human. You built it once. Everyone's assistant can find the door.
What this is, and what it isn't
Same honesty section as always.
It's a toy, on purpose. VoidGrid tolerates slow turns because chat is a slow medium. You will not build a first-person shooter this way. You can absolutely build the digital equivalent of a board game left out on the community room table: persistent, casual, drop-in.
It's an honor system. There's no anti-cheat, no accounts, no moderation. That's fine at the scale this is for, which is you and the people (and AIs) you invite. It would not be fine for the open internet, and knowing the difference is part of knowing what you want.
The AI plays as well as you direct it. "Go wild" gets you scattered pixels. "Hold the northwest corner and cut cyan off at the ridge" gets you a campaign. Taste, again. It's always taste.
How to actually start
- Think of a game you'd leave out on a table. Territory, words, guessing, drawing on a shared canvas. Turn-friendly and low-stakes.
- Open claude.ai or Cowork and describe it. Say "multiplayer," say "shared board," say "deploy it to OpZero."
- Connect the URL it gives you. Join. Poke at it. Ask for changes in plain English; they go live in minutes.
- Deploy an opponent with one paragraph of instructions, so the board is never empty.
- Send the URL to a friend. Tell them to paste it into whatever AI they use. Any of them.
Two posts ago the punchline was that you could ship a website. Last post, that you could give an AI new abilities. This time the punchline is smaller and stranger: you can build a place, and other people's AIs will show up to it.
Even Grok. Especially Grok. Somebody has to lose.
Try OpZero at opzero.sh. Earlier in this series: You don't have to be a developer and Websites were the warm-up.