Ask for a game and Cog writes you a playable one.

Paper with Cog uses Minecraft Java Edition 1.21.4. Join with your own Java account and the matching game version; no client mod is required. Bedrock players on iPhone, iPad, Android and Windows can join the same world in beta. Hosting-only Fabric worlds are Java only, and do not include Cog or their game-making tools.

These examples were built in real worlds from requests in chat. They show the kinds of jobs Cog can tackle; the result and time needed depend on the request, the world and your available AI allowance.

• Original designs Designed on the spot rather than picked off a list. A walk-in house shaped like SpongeBob, with rooms inside it. A pirate galleon out on the open sea, thirty thousand blocks of it.
• New games, loaded while you play Ask for soccer and Cog lays the field and writes the rules: goals that count, a scoreboard, pads that hand out snowballs, fireworks for the winner. Finished rules can load into the running server without a restart; designing and checking them takes longer.
• Canyons and waterfalls A gorge with terraced walls and banded rock, and water that falls off the rim into a pool that stays put.
• Lakes, hills and flat ground A basin with a proper shoreline, raised ground with a natural profile, or a plot levelled to build on.
• Landmarks Pyramids with a chamber you can stand in, watchtowers with a stair that climbs one block a step, castle keeps with walls you can walk along.
• Places to live, and places to fight Houses with doors that open and lit interiors, and arenas that are fair at both ends, symmetric to the block.
• Roads and bridges Routes that read the ground they cross, and spans over open water with the deck raised clear of it.
• Rollercoasters A loop of real track with a hill in it, powered rails to keep you moving, and a cart waiting at the station. Get in.
• Real redstone A hidden door wired block by block. Pull the lever and the wall slides across.
• Playing alongside you Mining, crafting, farming, fighting, fetching, and following you around.

Watch each of these get built →

A datapack changes what the world does: a goal that counts, a pad that hands you something, a timer. No datapack can change a picture. That takes a resource pack, a different file entirely, loaded by each player's own game rather than by the server.

In our cartoon-blaster demonstration, Cog made both: the item art in a resource pack, and the rules for an arena around it. Standing on a pad hands out the item, health appears under player names, kills count up the side, and the first to five wins.

Rules can describe more than the winning score. Red team and blue team, picked by standing on a pad. Anybody who arrives mid-round watching from spectator until it is over. Shots everybody can see, that go off where they land. Those are rules, and Cog writes rules.

The catch: a resource pack is your own game loading a picture, so it asks you first. Say no and you keep playing, holding the ordinary item. Nobody is thrown off a world for declining a texture.

Cog draws the item as a grid of characters with a palette, and deterministic code turns that into the actual image. It is the same bargain as everywhere else: the imagining is Cog's, and the part that has to be exactly right is not left to a guess.

Then they look at it. A first attempt at sixteen pixels is a lump, for the same reason a first attempt at a dragon is: Cog is drawing something they cannot see. So several drafts are drawn at once and measured, and the best goes back to Cog with the picture and one question. Would somebody know what this is at the size of a fingernail?

The measuring catches the failure that always comes first. Cog's very first blaster filled 96% of its own outline, which is to say it was a rectangle in nice colours, and it was handed straight back with that number attached. Drawn properly, with drafts and a round of looking at them, the same request comes back at 43%: a barrel, a grip, a muzzle, and daylight around all three.

First draft 96% a rectangle in nice colours

After looking 43% barrel, grip, muzzle, daylight

We are interested in bringing the same idea to other games, including Hytale. That needs its own integration, compatibility testing and hosting work. There is no Hytale world available to create in the current beta, and no release date or inclusion in the advertised plans.

When Cog plans "gather some wood, then build a road", they are reasoning about what you want (a route, a quantity, a material) rather than about one game's particular blocks. The part that is specific to a game is the layer underneath: the code that knows what a Minecraft repeater's facing means, or what the equivalent call looks like elsewhere. Another game would need its own tools in that layer, plus testing of everything that depends on them. The approach is reusable; compatibility still has to be earned.

Two ideas guide that work: asking in plain language and having Cog work out the details, described in How it works, and the habit of checking their own result afterwards, described in Verification. Each new game needs its own way to perform those checks.

On Paper with Cog, the companion runs on the server. You join using Minecraft Java 1.21.4, or Bedrock on a phone, tablet or Windows PC, and the address in your dashboard. The joining guide shows each step. A custom item may offer an optional resource pack. Other server types show their own requirements during setup. Bedrock on consoles, and Hytale, are not supported in this beta.