[[Video:Let's Play Terraria Pt. 1 "Hello World"|thumb|right|350px|"Let's Play" video of Red and Blue playing alpha Terraria multiplayer]]
The maximum number of players in multiplayer varies based on the settings of the server.
Multiplayer worlds function no different from single player ones, other than an increased monster spawn rate (which is not affected by the number of players, only by the fact that there is more than one player). The items in the player's inventory in single player are also available in multiplayer and vice-versa.
In multiplayer, the PvP and team buttons that appear at the top of the equipment UI can be used.
The PvP button allows players to activate PvP mode, which makes their attacks collide with and damage other players who also have PvP enabled.
The team options allow players to join color-coded teams. Players will be able to see how far from every other member of their team they are (in feet), a general indicator of which direction every other teammate is in, as well as how much health each member has remaining (if they are not damaged, no HP indicator is drawn). Players on the same team are unable to damage each other via normal means, even with PvP enabled.
Hosting a server
An older way to create local servers is with Hamachi, a tool that allows you to connect to other people within your Hamachi group.
Another way is use use a program called GameRanger which creates a room and people can join.
Guide to Hosting a Server (No Hamachi)
- N.B. This is for people who would prefer not to watch a video. However, there are plenty of resources on YouTube and all over the internet. This is not recommended for proper dedicated servers. You must use console to be able to keep it separate from client-side since as of 1.0.5 the in-game hosting tool lets you play on the same application as the one with that is running the server.
First of all there are few things to keep in mind. What kind of server are you hosting? Is it for a few friends just playing around or is it a large public server for everyone (preferably non-griefers) to use. The reason for it is the preformance issue (let's not get into this). In short have a good computer/Dedicated Server and good-reliable internet.
Now, the things we need to do are as mentioned above. The host needs to create a server, find the port it uses and then open that port. Seems a lot of work to play with friends but that's how most servers work.
Let's find our internal IP address first. If you already know your internal IP address (ie. the IP address for your modem) then just skip this paragraph. Go into the windows and open up the windows command prompt (cmd.exe). This is usually found by clicking 'start' button and typing into the search tool 'cmd'. Look for the cmd exe and launch it. From there you'll find the good-old DOS format window. Type in 'ipconfig' and a list will appear. Scroll all the way up and look for the... something-something "IPv4...". (If your IPv4 does not work try your default gateway address)On the right column of the same line you'll see your internal IP address. Remember it.
- N.B. Some version of the ipconfig like the XP does not show you the internal IP address (IPv4). Instead shows you the external IP address (so called local IP). You must look for it in the manual provided with the modem or you must look for it over the internet.
Now that we have our internal IP address, open your web browser. Then type in your internal IP address into the address box. Enter it and you'll find it asks for your password. It usually is user: admin, password: admin or password. If it isn't then someone who set up your modem has changed it, well good luck finding it... Once you're in the local page of your modem look for something in the lines of "application" or "port forwarding" or "gaming" (the reason it's so vague is that different types of modem have different layouts for their page). Create a new port forwarding. It usually is either just filling out a box and enable it (most people forget). If it isn't and its complicated, then try using this site to find out how to use your modem setup (note that it keeps asking you to buy stuff, don't, just skip it on the top right corner). The portforward website tells you how to set up ports but just learn up to how you can open up ports because Terraria has different ports.
Since we have the port number (7777 by default) type it into all the external port (both if you have a range) and internal port. Make a name for it if you want, so you don't forget. Activate the configuration.
Launch Terraria. Go to multiplayer. Start to host a server (via "Host & Play". Choose a map you already have or start a new one. Choose your character. By default the port is 7777. Leave it as that. Leave passwords blank if you want it to be open. It will tell you that the server is launched and tells you the port. Remember the port number (if its not 7777). You'll now be in the game with your chosen character. You do not need to port forward if it already has been open.
All you need to do now is to get the external IP address. You can do that with the one mentioned above or any other IP checker. When joining, you and any others must use the external IP address not the internal one. Also you must note some ISP will not give you a static external IP address so it may change when you restart your modem. Check it always when you restart your server.
If you are hosting and joining a game over the same modem, for example if you're trying to LAN on the same wifi connection at your house, then the IP address that you enter into the Terraria "Join" page is the same as your IPv4 number, not your external IP address.
Now you're ready. To test your server invite others to join your server.
If you want to make changes or modify your server you must use your Server Console.
The game has a built in anti-cheat mechanic, that will kick you if you try to cheat.
Sometimes though the game considers using the Aqua Scepter cheating, and you will get the message shown on the picture. It will also kick you for building too fast, using the Minishark and other fast projectile weapons in battle (especially Bosses). The Vilethorn is also a weapon that can trigger an auto kick. It can also kick the host. This is most likely a bug and was thought to be fixed in the future, but most likely will not be.