Portal 2: Multiplayer Mod (Complete Guide)

This guide shows you how to play the Portal 2 multiplayer mode with up to 33 players total!

What is this mod?

This mod allows both you and up to 32 of your friends to play in a single multiplayer match in Portal 2!

At this point in time, we are using VScript and a server plugin to add extra functionality to our mod. Some of our basic features include...

• Maximum player cap of 33
  
• In-game player nametags
  
• Lots of fun chat commands
  
• Custom player model colors
  
• Elastic player collision
  
• Player join/disconnect indicators
  
• Full singleplayer campaign support (Note: Can be a bit buggy)
  
• Full support for all three of the Gelocity Co-op workshop maps
  
• Support for Linux*, Windows 10 and higher

Much like previous Source Engine-based multiplayer titles from Valve, Portal 2 at its core shares an architecture that allows for running servers with more than 2 players. We have developed an easy-to-use GUI that anyone can use to accomplish this, however, due to the nature of how Portal 2 was coded, there are many nuances that will be highlighted in the below sections.

Disclaimers

For speedrunners:

• If you speedrun Portal 2, please be aware that this mod can invalidate your runs if uninstalled incorrectly. There is a strict ruling on the existence of custom and modified .nut files in your installation. You do not need to worry about this if you just want to join these modded sessions.

For casual players that want to join these matches:

• Only the host needs this mod. You just need to launch normal Portal 2!
  
• If you happen to also host these modded servers, make sure the mod is uninstalled before joining a session or else the game will break.

For casual players that want to host these matches:

• Port 27015 must be accessible via UDP. You can achieve this by Port Forwarding, or using 3rd party software like PlayIt[github.com]. (Make sure you use 0.15.25 as the latest version of PlayIt is currently broken)
  
• Windows users: In the event that Windows Defender falsely flags our executable as malware, you will need to add it as an exception in your system settings.
  
  1. For reassurance, our entire codebase is completely open source on GitHub[github.com].
• Should your game install break in any way as the host, it is recommended that you verify the integrity of the game's files through the Steam Library page and remove P2:MM-related files after this is done.
  
• P2MM only supports Linux through Proton.

Hosting the Server

Hosting a game is made very simple with our launcher.

1. Simply visit the latest release page[github.com] from our GitHub repository and download the file that applies to you:

• If on Windows, download p2mm-[version].exe
  
• If on Linux, download p2mm-[version].sh

2. Click "Start Game". The game will automatically mount the mod files into your installation and open Portal 2 for you. After the loading screen, you will spawn in the main coop lobby, at which point, your friends may try connecting to you.

• If the launcher fails to automatically find your Portal 2 directory, follow these steps:
  
  • Navigate to the portal2path setting:
    
  • Settings > Launcher Config > portal2path
    
  • Set this to the absolute directory of your target Portal 2 installation.
    (i.e. C:\Program Files (x86)\Steam\steamapps\common\Portal 2)
  
  
• Note: If your friends cannot connect to you at this point, you may have misconfigured your Firewall or Networking.

Joining as a friend

Joining is relatively simple, but make sure you have the developer console enabled first.

How to enable the developer console:

1. Launch Portal 2
2. While at the main menu, click on "Options".
3. Next, click on "Keyboard/Mouse".
4. Toggle the setting, "Allow Developer Console", to be "Enabled".
5. By default, the tilde key "~" located to the left of the "1" key on U.S. keyboards is bound to open the developer console.

• If tilde does not work, the bounded key can be found in the keybinding settings.

-------------------------------------------------------------------------------------------------------

How to connect to the host:

1. Make sure you're not loaded into any map.
2. Open the developer console.
3. Type in "connect X", but replace "X" with the host's public IP address.

• If you are joining a local host on your own network, then you need to enter the IPv4 address of the host computer.
  
  • If the host is running Windows, simply enter "cmd" in their Windows Taskbar search area, and then "ipconfig" inside of the command prompt that opens up. There will be a section mentioning this address.
  
  
• If you are joining the host through PlayIt, the host can find this IP in the PlayIt console window.

4. Submit the entry.
5. After the loading screen, you should be united with the host, ready to play!

Discord

If you need assistance setting up the mod or want to hang out with an awesome community, come join our Discord server! We’d also love to hear your feedback on how we can make the mod even better.

https://discord.gg/kW3nG6GKpF

Credits

Primary mod team:

• vista | VScript, Reverse Engineering, Source Plugin
  
• Orsell | Launcher, VScript, Reverse Engineering, Source Plugin
  
• \n | Launcher, VScript, Source Plugin

Mod contributors:

• kyleraykbs | Launcher, VScript, Reverse Engineering, Source Plugin
  
• Wolƒe Strider Shoσter | VScript, Reverse Engineering
  
• Bumpy | VScript, Reverse Engineering
  
• Nanoman2525 | Reverse Engineering, VScript, Source Plugin
  
• wanderer | Reverse Engineering, Source Plugin
  
• cabiste | Launcher, VScript
  
• QuantumCoded[github.com] | VScript
  
• AlexAdvDev | VScript
  
• DeaneAlistair[github.com] | VScript
  
• PieCreeper | Map Contributor
  
• Luukex | Translator
  
• Meb | Translator
  
• maldron0309[github.com] | Translator
  
• SummonHIM[github.com] | Translator
  
• WhatDidYouExpect[github.com] | Translator
  
• bentoemanuel[github.com] | Translator

If you liked this mod and want to support it, please leave a like on the page, and don't forget to share!

[\n]

I’d like to note that it is actually windows defender/whatever antivirus you use telling the browser if it thinks it’s malicious. Web browsers (chrome, brave, *dge, etc) generally do not have inbuilt antiviruses

[Orsell]

@Popper Weyu You just need to tell the browser to "download it anyway", sometimes when the popup occurs when you click it telling you it could be a dangerous file, there is usually a button that allows you to download the file anyway.

[Popper Weyu]

I've read the FaQ but it's not even windows flagging it as a virus, it's straight up my browser flagging it.

[Orsell]

Read the FAQ page on our GitHub repositories wiki. Please do that before saying stuff like that.

[FarmerGideon]

the file had a virus. I might suggest you use a earlier file

[Orsell]

@MaxFar there is the Portal 2 console which you can use to load maps directly. `map (mapname)` to start a map `changelevel (mapname)` to change to a different one while currently in a map.

[Orsell]

Make a help post on our Discord so we can help you there

[Nearvest]

Google refuses to let me download, can someone help me unblock it?

[Orsell]

Did you read the new guide in the wiki as well as the FAQ?

[someonerandom1982]

Google wont let me donwload it as it detects a virus