Underhell is a Source Engine game developed by the Underhell Team in collaboration with We Create Stuff. Underhell Chapter 1 requires ONLY Source SDK Base 2007 installed. No Source game is required.

Report article RSS Feed How to play Underhell - Coop (Unofficial version)

This small tutorial will explain how to play the unofficial Underhell Coop mode built into the engine. It is unstable, buggy, it will crash and lag, but it's possible to have fun.

Posted by Mxthe on Dec 15th, 2013
Basic Other.

Thought it would be good to start this tutorial by making this clear.


There is no Ingame chat, the ingame VOIP seems to work only when it wants to, launching the coop will keep your Steam in "Playing Source SDK Base 2006" forever, until you restart Steam.

Many entities built for the SP will crash the MP, some functions will be junky, dying and respawning will probably screw up the health system. You will not see your own bullet impacts in game, but you will see those of others.

Having said all that...It's actually a lot of fun.

Port Forwarding

Since there are no servers for this game mode, nor is it listed on the Steam master server, there is no server browser, and if you want to play, you are going to have to host.In order to host a listen server, you need to make sure that your router's ports are forwarded.

Steam uses ports 27015

The best website for Port Forwarding, is PortForward.com
Although this might seem overly complicated, I assure you it's not, and this is just the first obstacle in the way of killing infected with your friends.

Hosting a Game

First, you need to enable the Developer Console for Underhell, for that, you can add "-console" in the game launch parameters in the property tab when right clicking on it in your Steam Library.
Once you are in the Main Menu with the console, you have to type:


It is impossible to change the "maxplayers" when the game is currently running, and the background map of the menu is considered as a "game".
Once you have "disconnected" from the Menu Map, type:

maxplayers 4

Where the "4" can be any number from 1-16, although I'd recommend not having more than 4 players in a game, or it could get pretty crazy.Then enter the following:

sv_lan 0

This will tell the game, that any game created will not be running in Lan, therefore it will run on the internet.If your ports have been forwarded correctly, you can now launch any map, and it will be running online, and anyone can join you.

How to join your game

When you will be running a game, it will run on your current public IP address, which you will need to tell your friends.If you do not know your IP address, you can go to whatismyip.com.

You should get a number that looks like this:, now simply add the port number for the game, which is 27015, and your game's Ip address will be:

Now simply copy paste your IP address to your friends, and tell them to enter:


"Connect (ipaddress)" will connect to your server, you will get no Hud Warning" that someone is joining, but the console should print a message saying "YourFriend has connected" letting you know that he is joining.

Some things to set up

Underhell uses many features that were designed for SP, like serverside ragdolls that allows for extra damage, or the serverside gibs that can be interacted with.Running all that in a server will quickly cripple it, and will most likely cause lag and performance issues.
Therefore, it is recommended that you enter the following commands when trying to create an MP game, to optimize as best as possible:

coop 1

uh_maxseragdolls 1

uh_maxsergibs 1

I've never been really sure what the "coop 1" cvar did, but it was already there and it seems appropriate.As for the other 2, they set the max limit of server gibs and ragdolls to 1, instead of 8 and 16, which should avoid some issues.

Some useful stuff

When your game is running, and everyone is in, you will all be Casual Jakes, or the model of Jake in the house, wearing casual clothing.There are no player names floating above your heads, and no way to differentiate yourselves.So here are a few console commands that might be useful:First, type sv_cheats 1 to turn on cheats.

ent_fire !player

Press the space bar after entering this, and you will see all the available !player inputs.You can for example change the player model:

ent_fire !player setplayermodel

Here are the following functional models:


Now, if you want to change only YOUR settings, enter !self instead of !player, for example:

ent_fire !self setplayermodel models/player/jake_pmc.mdl

You can change another player's model, by pointing at him and using the !picker identifier, like this:

ent_fire !picker setplayermodel models/player/jake_inmate.mdl

You can use the "SetHeath" input to heal yourself or others, or you can use the "Color" input with RGB values to set yourself appart by being a unified color, be sure to use double quotes for the value:

ent_fire !self color "255 0 0"

This will make yourself look Red, practical to differentiate yourself (the host) from other players.

Finally, you might want to enable the Glow on the players, so you can see them through walls, to avoid losing each other.

ent_fire !player glow 1

You can keep experimenting with the other settings, just keep in mind, this is very unstable, and many commands will not work as intended.

What to play?

Now that you know how to set up a game and set up some things for convenience, you must be wondering what to play?Well truth is, almost none of the Single Player maps will work correctly in coop.In fact, the Objective System will CRASH the MP.So if you are running a map of the SP, make sure to kill the objective entities by entering the following:

ent_fire mainobjective kill

ent_fire secondaryobjective kill

Killing these 2 entities should avoid some crashes, but something else will probably end up crashing the game anyway, there are so many scripts in the SP that are not meant for MP.
So, what to play may you ask?

Well during the COOP testing, I used a map created by an old friend of mine called Alex Roycewicz to test the system.
I decompiled and edited the map to add Underhell entities, and added randomized spawns of enemies, along with a few randomized events.

The original map can be found at: Css.gamebanana.com

The Underhell modified for coop version can be found at:
(Make sure the file gets downloaded correctly, these servers can wonky sometimes.)

Unpack this file in your Sourcemods/Underhell/Maps folder, make sure the map is right next to the other maps of the game.Then launch the map by typing in the console:

map dotd_crookcounty_night

This map was designed specifically to test the Coop, and unless you do some fonky things, you should be able to play it rather crash-free. No promises though.

What's the objective?


This map has infinite waves of enemies, separated by an "Outbreak" event which will change the fog and lighting, as well as how the map plays out.Items can be found in buildings, but they will only respawn when you are far away from them.If you die in the MP, it will cause some issues, so it is advised to NOT die, which should be your primary objective.
Try avoid using Cheats, like giving yourself a minigun. I know it's REALLY fun at first, but after 5-10 minutes of doing this, you will grow tired of it, and going back to play without cheats won't be as "exciting", so keep the cheats for later.

Here is a list of the Underhell Entities which you can spawn with the following command:

ent_create "entityname"


ent_create item_healthkit

This will create an entity where you are currently looking.

Post comment Comments
Shizzzler Dec 15 2013 says:

And there it is!
Original Underhell concept, which from the beginning was supposed to be a cooperative survival!

Will leave a feedback as soon as I will test it out

+10 votes     reply to comment
Chad51 Dec 15 2013 says:

Incredible, looking forward to when it is fixed up!

+5 votes     reply to comment
Tordiff Dec 15 2013 says:

I use hamachi, anyway I can't wait to play this with friends!

+3 votes     reply to comment
why_me Dec 15 2013 says:

Could we possibly see a TDM mode with friendly and enemy AI in the future? Or maybe a wave based mode with friendly AI?

+6 votes     reply to comment
[FH]Gorgutz Dec 15 2013 replied:

Always thought of this, would be great to see implemented.

Especially in the labs where you're trying to turn off gas and zombies are just charging you through the gassy smoke and you're already restricted on vision because of the gas mask.

A co-op Stealth gamemode would be really neat too.

+5 votes     reply to comment
why_me Dec 15 2013 replied:

I was thinking of the first level before you go deep underground. An urban environment TDM with vents and indoor environments to hide in or take cover in would be pretty cool. I wonder what Third party maps people would come up with too.

+2 votes     reply to comment
WeeGee9000 Dec 15 2013 says:

In short: I can now *fanboy scream* with a friend :D

+4 votes     reply to comment
orang3dragon612 Dec 15 2013 says:

At last! Just like I had always hoped from 2011, the start of Coop has begun. Definitely looking forward to this, and good job with it. Have to ask, what's been the hardest part of coding this beast? Also, will focus be, er, focused on this till completion, or will Chapter 2 be worked on too? Keep up the great work guys. Hoping for the best. Can not see why this couldn't be sold commercially at this point.

+4 votes     reply to comment
Shizzzler Dec 15 2013 says:

Alright so I tested it out with my friends
A hell of a lot of troubles were when we tried to host it with 2 or 3 players for some reason
It was perfect with 5 of us
First we played it while having nearly all entities disabled. We were basically roaming around the Cantina map
When switching to Jake inmate model, everyone had a crash. No matter who hosted it
Also we were experiencing weird model bugs when the weapon raising were performed by host only
Other than that, we expected that I will be extremely buggy, but it turned out to be very well playable at this state

Half of the problems that you described, that might occur, didn't occurred at all

All in all its in a pretty good shape right now!
We really enjoy it

+4 votes     reply to comment
natestross1052 Dec 15 2013 replied:

Man you forgot about silencer and other player models

So we also tried to load up other player models
None of other models worked
Except for Hector
But whenever we tried crouching, it was making another goofy animations
Also, trying to attach silencer on G36 causes crashes

+4 votes     reply to comment
ViolentValentine Dec 16 2013 says:

Yeah... I'll still wait for official patch

+5 votes     reply to comment
natestross1052 Dec 16 2013 replied:

Suit yourself
It's totaly worth it at its current state

+3 votes     reply to comment
Versa-Life Dec 16 2013 says:

I'll wait until this is hopefully bug-free. Got too many other games to play!

+3 votes     reply to comment
Tordiff Dec 16 2013 says:

I played co-op using hamachi before this guide I used disconnect max players 4 and net_start and map uh_house1 or whatever it was called but it was ultra buggy thanks for the guide mxthe it will feel a lot more playable now!

+2 votes     reply to comment
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LeeoryHarold Dec 18 2013 says:

Exactly what I was thinking ! But I was thinking not coop... But a survival game where you are whoever you want (playermodel I mean)and you have a custom story you need to pick from (depends the model). Like you are a prison guard and you need to pick a story like : "I saw some crazed prisoners attacking my fellow partners so I ran and hide with my gun.Now I need to find other survivors and food". And you have some properties at some models. When you are a guard you can choose from the males a model.And if you are a prisoner or an office survivor you need also to choose the gender and the models.
Hope someone will do this for the mod and it's chapters.
Happy reading.

+1 vote     reply to comment
jakey1995abc Dec 19 2013 says:

Looking forward to an official release :D

+2 votes     reply to comment
natestross1052 Dec 21 2013 replied:

What the **** are you talking about?
This is official release...

-1 votes     reply to comment
khangtommy Jan 24 2014 replied:


+3 votes     reply to comment
Gundam919 Dec 20 2013 says:

i would love to see the team behind underhell to be able to make a chapter 2 with co-op if it does get implemented into the game.
it is still awesome as a single player but i would like to see if it was going to be something like a 2 player co-op that the return of the hermit would be a grateful for a lot of us because the hermit seems very cheery even when the outbreak is going on.

+1 vote     reply to comment
Rumple-Chan Mar 14 2015 replied:

Sorry to tell you this m8, but Hermit isn't around after chapter 1. Collect all the cards and you'll know what im talking about. Also, reason he acts the way he does is because he is completely oblivious to whats actually happening, he doesnt know the people are zombies basically.

+1 vote     reply to comment
WMan22 Dec 23 2013 says:

I always figured that there would eventually be a seperate prequel coop campaign featuring Bryan and Junior.

+1 vote     reply to comment
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