Classic DOOM Steam Guide

How to play DOOM Classic Complete on Steam as if it were released today

This guide is outdated. For most people, the Unity port of DOOM, which is sold on Steam, is good enough.
You can still apply this to replace either the Unity version or DOS version with a source port.


I have seen a lot of posts asking "What's the best way to play DOOM on Steam?"


"Just got DOOM on Steam, what's the best DOSBox alternative for modern displays and computers?".

Although a lot of people might prefer playing DOOM through DOSBox, after all that's how the game looked and played in 1993 which I respect but I, like many others, want to take advantage of the higher resolution displays and the faster computers of today.
I find it more difficult to play the game at the low resolution of the DOSBox emulator.
You can just play the Unity release though. It's good enough for the majority of people and also invalidates a lot of the points I make in this guide (I'm only updating the important parts), but this is for those who want more.
This is where source ports come in.

Source Ports:

Source ports are the best way to achieve the most of our goals.
I'd recommend checking out any of the following:

  1. Chocolate DOOM
  2. Doomsday
  4. ZDOOM

If you need to know more to make your decision, check these:

Here's a full list of source ports: Wikipedia
Here's a comparison of a few popular ones:

The source port I use myself is GZDoom, it's an improved and updated version of ZDoom.

It's also a portable source port, which will be useful later.

When choosing and downloading your source port I recommend not using the installers (these will be labeled as an installer or will be in a .msi package)

Portable installations will usually be in a compressed folder like a zip or rar, so look for those when on the download page!

Click the following red text to show a post made by phobos876 explaining the source ports

I have a bit of a guide post, so i guess it could help too:
  1. The classic collection on Steam or GOG has Ultimate Doom (First game with an additional fourth episode), Doom 2 (Which may have the Master Levels) and Final Doom (Two 32 maps episodes, which are a bit more difficult and not as enjoyed as the main two games).
  2. people play Doom with source ports and there's a lot of them for Doom games.
  3. Chocolate Doom is the most faithfull one, while Crispy Doom is like a slighty "friendlier" version of Choco.
  4. PrBoom and PrBoom+ work as vanilla source ports with some additions. I think the latter can play maps that are still vanilla but have lots of enemies if i'm right.
  5. GZDoom is for gameplay mods, advanced modding projects and has a lot of settings and features. It's more advanced than other source ports but it's not as faithfull (Either due to some default settings or outright changes), some of its default settings are kinda bad (You can change them if you can browse the options menus) and can be a bit heavy on certain hardware (Which means PrBoom+ can handle huge maps better, if i got that right).
  6. Zandronum is also mod focused but for multiplayer.
  7. ZDL is a launcher that allows you to set up orders for which content you want to play (Such as a mapset, then one or two gameplay mods after it). Normally, you put the maps/wads before the gameplay changing stuff, while selecting a specific IWAD, that the map/mapset/wad is made for.
  8. IWADS (As in, the games themselves like Doom 1, 2 etc) should be in the same folder as your chosen source port but source ports themselves should be on seperate folders. (Which means you may have to copy+paste the IWADS into each seperate folder)
  9. To get mods or wads, you can check sites like Doomworld's idgames, ZDoom forums, ModDb or maybe simply google mod related stuff and see if a forum thread or video description have a download link. Doom modding/mapping is big enough that there's a lot of places to get that content.
  10. There's also YT channels dedicated to Doom mod stuff and even Tumblr blogs.
  11. Doom 64 has its own source port, which is Doom 64 EX, but it requires a Nintendo 64 ROM of the game.
  12. If you want to play Doom 3 (And its expansion Resurrection of Evil), you could see the original game and its expansion and mix them with the duct tape mod, if you're worried about the changes in the BFG edition.

I tried to add as much info as possible and someone once made a Doom guide, so i hope this one can work too.

Also, here's this.

Making it play like every other Steam game:

This part will need to be explained.

What I mean by making it play as if it were released today is this: You buy a game on Steam, you download it and when you launch it you expect to be able to use your full desktop resolution, to use similar controls to modern FPS games, to start the game through Steam with the Steam overlay (and/or the Discord overlay) and to have your playtime tracked while you play. The problem is that you (without this guide) would have to choose between a more comfortable experience using a source port or the experience Steam provides though DOSBox.

As stated on the Doomsday source port website:

"Modern games are held to higher standards of visual fidelity, usability, and multiplayer features."

So, you may be wondering, how do you play a source port through Steam? The answer is kind of weird but it works well...

What you'll need:

  1. DOOM on steam (I recommend buying the Classic Complete bundle)
  2. A DOOM Source port with a portable installation
  3. Some sort of zip manager for backups, I use 7ZIP


  1. First We'll make a backup of the game, in case you dislike using the source port in the end. So navigate to the folder of the game you want to run though a source port, I'll be using Ultimate Doom so I'll go here
    C:\Program Files (x86)\Steam\steamapps\common\Ultimate Doom\
  2. I'll be using GZDoom for this so I'll go to here and download GZDoom.
  3. In DOOMs install folder, open the \rerelease\ folder and delete its contents.
  4. Extract GZDoom into the folder
  5. Rename the "GZDoom.exe" to "DOOM.exe", you'll notice the icon changes but it's still GZDoom.
  6. Now copy your DOOM WAD file form the \Ultimate Doom\base\ folder and place it in the \Ultimate Doom\rerelease\ folder.

That's all it takes, just repeat this for the other DOOM games like DOOM II or whichever others you own.

If you also used GZDoom, you can use its per executable config to you advantage for all the games other than Final Doom (since it has two possible wads to choose from). For single wad games like Ultimate Doom or DOOM II etc. you can set GZDoom to autolaunch the last wad, so for Ultimate Doom, it will launch right into the game but for Final Doom you'll need to choose your WAD from the list every time.

If you used GZDoom:

Start the game through Steam, you'll see the GZDoom dialogue pop up, highlight Ultimate DOOM on the list and tick the "Don't ask me this again" box and press Play. From now on it will skip that step and launch right into DOOM.

What has this done?

We have basically just tricked Steam into thinking we're using the Unity release of DOOM when we're actually using a source port, this means we can use the Steam overlay and we can have our play time tracked as expected.
Since DOOM won't be getting any updates any time soon (Other than the one it got in 2020???), this is going to work forever.
Now you can use your Source Port to play using mods like Brutal DOOM, which, for me personally, really brings the game up to date.


Thanks for reading and/or following along, I hope you enjoy your time playing DOOM! Note: Although it is most likely that most if not all of this has been discussed in replies on threads,
I thought I would group it together for anyone you had just bought the game on Steam and was looking for the best way to play it.

Site created 30/11/19. Last updated 19/04/21
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