How to Install Factorio and Join a Server

Nobody has ever joined a Factorio server for twenty minutes. You connect to see what a friend has built. You notice the iron smelting is short by about forty furnaces. You start fixing it. Then it is two in the morning and you are drawing a rail junction on a piece of paper.

That is the game. It is also the reason multiplayer Factorio is a different proposition from most co-operative games: there is no round and no session and no natural stopping point. There is a factory that exists whether or not you are looking at it, and it is always behind.

Factorio is a top-down automation game from Wube. You land on a planet, mine ore by hand for about four minutes, then spend the next several hundred hours never touching ore by hand again because you built something that does it. Listings for it collect on the Factorio hub, and this guide covers buying it, understanding the three things that have to match before you can join anybody, and getting connected.

Buying it

Factorio is a paid game with two legitimate routes: Steam, or directly from the developer as a DRM-free download.

The unusual part is the price, which does not move. Wube has been publicly consistent about not discounting the game, and it has not been in a sale in its entire commercial life. So there is no point waiting for one, and any listing offering it cheaper than the official price is not a listing you should trust.

The two purchase routes produce the same game and they play together. If you buy from the developer's site you can attach it to Steam later, and the account you register there is also what the in-game public server browser uses to identify you.

There is a demo. Play it. The first hour of Factorio is a genuinely good tutorial and it will tell you within twenty minutes whether this is a game you are going to lose a year to.

Hardware, which is not what you expect

Factorio does not care about your graphics card. It cares about your processor, and specifically about how fast a single core is.

The whole game is one large simulation stepping forward sixty times a second, and every belt and inserter and machine in the factory is part of that step. A small factory runs on anything. A very large one eventually hits a ceiling where the simulation cannot keep up, and the game slows down for everybody rather than dropping frames.

This matters for multiplayer specifically. Everybody's client simulates the same world, so the slowest machine in the game is a problem for everybody, and a server hosting a late-game megabase needs single-thread performance rather than cores. Memory matters too once maps get large.

None of this is a concern for a new factory. It becomes one about two hundred hours in, which is roughly when people start asking about it.

The three things that must match

This is the section to read before you try to join anybody, because almost every failure to connect comes down to one of these.

The game version. Factorio multiplayer requires an exact version match between client and server. Not close. Exact. If the server is on one release and you have taken an update, you cannot join until one of you moves. Steam updates automatically by default, which is how most people discover this.

The mods. Every mod the server runs has to be on your machine at the same version. Mods the server does not run cannot be active on your client. The game handles this better than most: when you join a server running content you lack, it will tell you what is missing and offer to fetch and enable it, then restart itself. Let it. Trying to assemble a mod list by hand to match somebody else's server is unnecessary work.

The expansion. The paid expansion changes the base game substantially, and a world running it is not a world a client without it can enter. Check which one a group is playing before you spend an evening on the wrong one.

Two of those three are the same problem in different clothes: this is a deterministic simulation, every machine has to be running identical code, and the game is strict about it because the alternative is worse.

Connecting to a server

Open Multiplayer from the main menu. There are two routes and you want the second one.

Browse public games shows servers that have chosen to be listed. It requires you to be signed in with a Factorio account, which is free and which you already have if you bought the game from the developer's site. This list is fine for finding a random public factory to join.

Connect to address is the one that matters. Paste in the address and port of a specific server and it goes straight there:

203.0.113.77:34197

Factorio's default port is 34197, and it is UDP rather than TCP. That is worth knowing for two reasons. It is not the 27015 that Source games use, so an address copied from a listing will look unfamiliar. And a host running several Factorio servers on one machine has moved most of them off the default, so copy the full address including the port rather than the part before the colon.

A server can also require a password, and one that does is a private group's server rather than a broken one.

Once you connect, the server sends you the entire map. On a large factory this takes a moment and shows a progress bar. It happens again if you desync, which is the next section.

Desync, and why it is not your fault

Factorio does not stream the world state to you continuously. Every client runs the same simulation from the same starting point, applying the same inputs in the same order, and arrives at the same result. This is why the game can support very large factories over ordinary connections — it is sending keystrokes rather than the state of forty thousand machines.

The failure mode is called a desync. Your simulation and the server's diverge. The game notices, and it drops you back to a state everybody agrees on by re-downloading the map. You will see a message and a progress bar, and then you are back in.

It is annoying and it is usually not something you did. Mod interactions, a mismatched version that slipped through, and occasionally a genuine bug are the causes. If it happens once, shrug. If it happens every few minutes to one person, that person should verify their game files and check their mod list against the server's.

What playing together is actually like

Nothing in the game divides the work for you. There are no roles, no ownership, no permissions beyond what an administrator sets. Anyone can build anywhere and anyone can deconstruct anything.

That works far better than it sounds, provided a group settles two questions early.

Who owns the bus? Most factories grow around a central spine of belts carrying base materials. If two people restructure it simultaneously in different directions, the factory stops. Agree on who is doing the surgery before anybody starts.

What are we doing next? Factorio has an enormous number of valid next tasks and no prompting. Groups that work well tend to split by area rather than by job — you take oil processing, I will fix the smelting, someone else handles defence — and then leave each other alone.

The etiquette that emerges on public servers is worth knowing before you join one. Do not deconstruct somebody's build to replace it with your own without asking. Do not take the last of a resource everybody is waiting on. And if you break something, say so in chat rather than quietly walking away from it, because a factory with an unexplained fault in it will consume somebody's entire evening.

Biters, and the thing that kills servers

The planet is inhabited, and the inhabitants object to pollution. Your factory produces a cloud of it that spreads outward, and nests inside that cloud send attacks. The longer the game runs and the more you pollute, the nastier the things that show up.

This is the mechanic that punishes a group for building outward without defending. A factory that has quadrupled its output in a weekend has also quadrupled its pollution, and the defences that were adequate on Sunday are not adequate on Wednesday.

Servers can be set up with the enemies disabled entirely, and plenty of public building servers are. If you want the game to be purely a construction puzzle, that setting exists and choosing it is not cheating. Check what a server runs before you turn up expecting one or the other.

Hosting for a group

Two options, and the difference matters more here than in most games.

Hosting from inside the game is the quick route — load a save, host it, invite people. It works, your machine is both playing and serving, and the whole thing ends when you close the game. For a Factorio group that is a real limitation, because the entire appeal of a shared factory is that somebody can log in on Tuesday afternoon and fix the copper shortage.

The alternative is the headless build, which ships with the game. It runs the simulation with no graphics at all, takes a save file and a JSON settings file that controls the server's name, its visibility in the public list and whether it requires authenticated accounts, and it will happily run on a very modest machine until the factory gets large.

If you go that route, a few things are worth reading first. How many slots a game server needs is relevant in an unusual way here, because Factorio's ceiling is the simulation rather than the player count — four people on a huge map is a heavier job than twenty on a small one. Game server hosting costs covers what you should expect to pay, and where to host matters because everybody's inputs travel to the same box.

For a private group, decide early whether the server is public. A listed server gets strangers, and strangers in a shared-build game are a different proposition from strangers in a shooter. Running a whitelist that people actually apply to is about the middle path.

Problems

"You are not able to join this game." Version mismatch, nearly always. Compare the exact release numbers.

The mod download loop. The game fetches the server's mods and restarts, then asks again. This points at a mod that failed to download or one that is present at the wrong version. Clearing the local mod folder and letting it fetch everything fresh resolves most cases.

Connection times out. Check the port, then check whether the host has actually opened it. Factorio uses UDP, and a firewall rule written for TCP does nothing.

The game runs slowly for everybody at once. That is the simulation rather than the graphics, and it means the factory has outgrown the machine running it.

Where to go next

The closest neighbour is Satisfactory, which is the same idea in first person and three dimensions, with a co-operative multiplayer model built around a persistent shared world. Foundry sits in similar territory.

If the appeal is the shared persistent world rather than the belts specifically, Eco builds a whole economy and a set of consequences around it, and Vintage Story does something comparable with a much slower crafting curve. For the top-down, build-a-base-with-friends version, Terraria, Necesse and Core Keeper all run their own dedicated servers and all reward the same patience.

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JoinGG is a live directory of community game servers. Every listing is queried directly every fifteen minutes, so the player count you see was measured rather than reported by its owner, and each one carries a copyable connect address. Factorio servers are listed here, and every game on the site has its own hub. Player counts across every game are on the statistics page.