As you all know, last year Valve have released a massive update for Half-Life in honor of its 25th anniversary, which also brought to us very cool and useful feature called "Steam Networking".
In this guide I want to show you how to install and start playing Half-Life: Decay on PC as fast as possible without any external software, since most of older guides are obsolete and too complicated for casual user.

If you know what is Half-Life: Decay, don't read the text below, just skip straight to the first step.

Half-Life: Decay is a cooperative expansion, which was released as part of Half-Life version for PlayStation 2.
Originally developed by Gearbox Software, who also are known for such expansions as Half-Life: Opposing Force and Half-Life: Blue Shift.

In the game you play as doctors Gina Cross and Colette Green, who are working at the Anomalous Materials Labs at Black Mesa and assisting in setting up the experiment for Gordon Freeman.















Even though this expansion was originally developed exclusively for PlayStation 2, two Ukrainian developers decided to port it on PC for all the fans, who wanted to experience yet another piece of Half-Life story, but didn't have PlayStation 2. After two years of development, with the help of other enthusiats, Decay for PC was finally released in September 23, 2008.

You can download the installation file from archived copy of PC port's official site[web.archive.org], from the official ModDB page and, in case if it won't work for you or it will be taken down, I've uploaded the same file on my Google Drive[drive.google.com]and Mediafire[t.ly]
If you, for some reason, don't want to use short URL or it will stop working, then you can copy a direct link to download page on Mediafire (remove the space before "com"): mediafire. com/file/nt50r4e6447zvo8/decay_eng.rar

First note: you should have Half-Life installed on your PC, because Half-Life: Decay is working as a mod for Half-Life.

Second note: Steam Networking is present only in 25th anniversary or newer version of Half-Life. For older versions (e.g. pre-25th anniversary version known as "steam_legacy") you will need to have a publicly accessible static IP address or to use an external software, such as "Hamachi" or others.

That's why, before starting the installation, you need to make sure that you're using the latest version of Half-Life. For that, open your Steam library, click Right Mouse Button on Half-Life, press on "Properties", proceed to the tab called "Betas" and make sure that you have "None" as your chosen option, as it is shown in the screenshot below.

When it's done, you should necessarily exit Steam.

























After that launch the installation file, proceed further as usual, and when this little window will pop-up, choose "common" and press OK.






















Then it should automatically determine location of your Half-Life folder, like it is in the screenshot below.






















If somehow it didn't happen to you, click on "Browse..." and proceed to your "Steam\steamapps\common" folder, click once on the folder called "Half-Life" without opening/expanding it and press OK. Then delete anything what will appear after "...\common\Half-Life\" in the path and type "decay" (without quotation marks), so it will look exactly like in the screenshot above.
After that proceed as usual and finish the installation.

Now that the installation is over, you can launch Steam again and you should be able to find Half-Life: Decay in your library. But don't rush to start it right away, because there are few simple yet important things left to do before starting the game.

First of all, I recommend you to install my fixes for UI errors and missing localization, which appeared after Valve's 25th anniversary update. Without it, there will be missing text strings for different functions, which could confuse you.

You can download it from my Google Drive[drive.google.com]and Mediafire[t.ly]
If you, for some reason, don't want to use short URL or it will stop working, then you can copy a direct link to download page on Mediafire (remove the space before "com"): mediafire. com/file/ka0rh21ff5cqoio/Recreated_WON_menu_for_Half-Life_Decay.rar

Note: If you're worried about VAC ban - there's no point for that, because this patch includes only edited text files and images, which don't even replace original files, you can check it by yourself for more reassurance.

It also includes recreated by me unique WON-styled menu, which was created by the developers who ported Decay on PC. Similar as Valve did for original Half-Life.

You can read more about it and check the screenshots in the guide listed below:

https://gtm.you1.cn/sharedfiles/filedetails/?id=3351316035
Installation is very easy:

1. Open your Half-Life directory, which is located in "Steam\steamapps\common", or go to your Steam library, press Right Mouse Button on Half-Life, hover your cursor on "Manage" and click on "Browse local files".

2. Open the downloaded archive. Now, if you're playing with resolution 1024x768 and higher - open the folder called "High Resolution", and if you're playing with lower resolution, then open the folder called "Low Resolution". After that drag the folder called "decay_addon" into your Half-Life directory.

There is also a game icon for Steam library, and if you want to install it (which is easy, but not necessary), then in archive proceed to the folder called "decay", drag and replace the file "liblist.gam" in the same folder in your Half-Life directory ("Half-Life\decay"). After that do the same with file called "icon_big" in "resource" folder ("Half-Life\decay\resoruce").

Note: Game icon for Half-Life: Decay will appear in your library after you'll restart Steam.

3. When the process of copying files will be finished, launch the game, click on "Options", go to the tab "Content" and check the option which says "Allow custom addon content", as it is shown in the screenshot below. Then press "Apply" and the game will restart automatically.


























Now we can finally move to starting the server.

At this point, all you need to do is to press "Play Decay", in popped up window choose the map called "dy_accident1" and check the option "Enable Steam Networking", which will make your server appear in the server list.


























Note: If you want to play alone by using both characters (press "G" in game to switch between them) or with your partner on the shared local area network, in these cases you don't need to enable Steam Networking.


Then open the second tab called "Game", where you need to enter the server's name and password, which your partner will need to use in order to join to your server. After that press "Start" and wait for the game to load.



























Finally, it's time for your co-op partner to join. All they need to do is to open server list by pressing "Multiplayer" (or "Find Servers", if they're still using default unmodified menu), click on the tab called "Internet" (or "Lan", if you've created the server for your partner on the shared local area network without enabling Steam Networking), double-click on your server in the list or press Right Mouse Button and click on "Connect to server", then enter the password and press "Connect".


























And that is all, have fun and enjoy your journey in Half-Life: Decay!

Sometimes, when you or your co-op partner will try to join the server, you might be kicked with this error popped up:


























Usually it means, that there are two players on the server named Colette: one is your partner and another one is a bot.


























To fix this, ask your partner to switch his character back to Gina, then to disconnect, restart the server and to not switch his character until the moment you will connect and appear on the server.
If it didn't work, then player which hosts the server should disconnect, restart the game and host the server again.

Gearbox Software - a company, which developers created Half-Life: Decay.
A team of passionate enthusiasts[web.archive.org], who ported the game on PC.
Me - a person, who created this guide.

If this guide was helpful for you, then I would appreciate if you give it a like and add to favorites, so it will be higher in the list of all guides and, therefore, easier for others to find.
Also, if you have any issues or questions - share them in the comments and I will try my best to assist you.

Have a very safe day.