This gamebanana mod provides multiplayer related buttons for the main menu. It is recommended you install this, if you're using a listen server.
Download it here[gamebanana.com].

Sourcemod and Metamod can mostly fix a majority of the problems when hosting MP servers. However, some additional files are required for Sourcemod to run correctly in HL2.

Download Sourcemod: https://www.sourcemod.net/downloads.php?branch=stable
Download Metamod Source: https://www.sourcemm.net/downloads.php/?branch=1.12-dev
Download required HL2 Gamedata: https://github.com/SourceSPMP/sourcemod/archive/refs/heads/main.zip

Since you've downloaded the zip files from the two sites provided. you will have to extract the files, and put it in the 'ep2' folder. If you're aiming to play the game in Episode One, or regular Half-Life 2,

You will have to extract the zip files into the 'episodic' folder (for Episode One)

If you're aiming for the regular HL2, extract the zip files into the 'hl2' folder.

Make sure the game folders contain the newly added 'addons' folder. If you have extracted the zips, and there are folders named after the zips, move the files in these folders out of the zip folders, and delete the folders since they won't cause any effect on your game.

Since sourcemod and metamod were intended to be used in dedicated servers, it may have some unknown issues while running it in your game.


Making a dedicated server is really easy.
You need to copy srcds.exe from Source 2013 Dedicated server, and paste it to the Half-Life 2 directory. (NOT in the hl2 folder)

Another file is required to be pasted in the half-life 2 bin folder. (NOT in the hl2 folder)
You will need to copy the dedicated.dll from the bin folder, and paste it into the Half-Life 2 bin folder. Like i said earlier, do not paste it into the hl2 bin folder. It won't work if you do it that way.

If you are going to use a listen server, consider launching the game.

If you have the developer console enabled, you will need to set the maximum players.
First, if you're in a background map, type 'disconnect' in console.
Then, when you've disconnected off of the server, you will need to type 'maxplayers 32' in console. This will provide multiplayer capatibilities.

I have created a plugin in the past that fixes some bugs with the multiplayer servers out there.
Download the plugin here[forums.alliedmods.net], head over to your game folder.
Go to the addons folder, the sourcemod folder, and then the plugins folder. Move the SMX file in there.

If you're already running a server, you will need to type 'sm plugins refresh' in console.

Since you've installed the misc fixes mod, you will need to make some changes to your plugins folder.
Move giveweapons, smgjumping, nextmap, bhop and chat plugins to the disabled folder. You will need to restart your server if it's running after you've done that.

Finally. Now that you have figured out how to make a sort of non-crash prone server, you can finally play the game with your friends!

Here are a list of bugs that usually involve multiplayer:

Blowing up zombies and headcrabs crashes the game.
Picking up turrets crash the game in the prison levels.
The playermodel is really crusty and isn't animated.
NPCs don't look at you
Most episodic maps crash the game.
NPCs that were programmed to follow you don't follow anyone in MP.
Looking at a NPC doesn't trigger anything