For those who are new to the Classic Doom scene, the sheer number of WADs and source ports can be overwhelming. This guide is an attempt to clarify things and provide some simple, useful information for newcomers.     PART 1: Getting DOOM   This guide assumes you have all 4 of the Classic Doom games - Doom 1 (The Ultimate DOOM), Doom 2, Final Doom: Evilution (TNT) and Final Doom: The Plutonia Experiment. You can get them legally at GOG or on Steam:   The Ultimate Doom on GOG Doom 2 + Final Doom on GOG Doom Classic Complete on Steam (Note: Doom Eternal actually contains the Doom 1 & 2 IWADs themselves in the Doom Eternal/base/classicwads directory. They work fine for singleplayer, but will need to be downpatched for multiplayer.)     PART 2: Choosing a Source Port   A source port is a program that can run Doom. They come in many different flavors and for many different operating systems. No matter what hardware you have, you'll be able to find a port that suits your needs. Note: Some source ports will require the IWADs (doom.wad, doom2.wad, etc) to be placed inside the port's directory, however most can make use of the DOOMWADDIR environment variable.   - GZDoom - This is the most popular source port. It has many features, by far the widest compatibility with WADs and Mods, and runs on multiple operating systems. LZDoom is recommended for those running older hardware which cannot handle the latest versions of GZDoom.   - DSDA-Doom - Port tailored to speedrunners with quality-of-life improvements for demo recording, and fun additions to the demo playback experience. Runs all vanilla and Boom-compatible WADs.   - PrBoom+ - Before DSDA-Doom, this was the port of choice for demo recording and speedrunners. It has very faithful behavior to the original engine and runs all vanilla and Boom WADs. Features high resolution and many QoL improvements.   - Chocolate Doom - This is the port of choice for oldschool purists. It accurately reproduces the experience of Doom as it was played in the 1990s, complete with 320x200 resolution. It is compatible with all vanilla WADs.   - Classic Doom Unity Port - This comes free with Doom if you buy it through Steam. It has raised limits compared to vanilla Doom, and support for loading custom WADs, simply place them in the "C:\Users\<user name>\Saved Games\id Software\DOOM 2\WADs" directory.     There are many more source ports available and they are tailored to just about every preference you could possibly have:   - Source Ports subforum - List of Doom source ports - Comparison of active source ports   (If you are looking for Classic Doom Multiplayer, the 3 source ports commonly used are Zandronum, ZDaemon and Odamex. More information about Multiplayer Doom can be found in this tutorial and at the Multiplayer subforum.)     PART 3: Downloading WADs and Mods   A huge part of what makes Doom so fun are the thousands of WADs and Mods available. People have been making custom content since 1994 and have never stopped, so there are lots of frags to be had! Here are some helpful links for finding custom content.   Best WADs - These WADs are winners of the famed Cacowards, a selection of the 10 best WADs from every year since 1994. Generally considered the cream of the crop.   Doomworld's idgames frontend -  idgames is the longest running archive of Doom WADs and related files. You can find all of the latest WAD releases on this page!   Doom and Doom 2 on Mod DB - You can find a vast array of content here. Mod DB allows you to sort by popularity, upload date and more, so finding content is easy.   Wad Archive - An extremely large repository of over 76,000 WADs from every year since 1994.   Best Deathmatch WADs - My own personal selection. If you prefer PVP style gameplay, you'll have a blast on all of these.   There are many more places to find WADs, but these are plenty to get you started!     PART 4: Selecting a Launcher /Frontend (optional!)   Most source ports allow you to simply drag-and-drop WADs onto the port itself, or allow you to copy your WADs and paste them on the port, meaning launching custom content is very easy. However, some prefer using a launcher since they can load multiple WADs at once, record demos, and save configurations so you can start the game however you want each and every time.   ZDL - One of the most popular launchers, compatible with any source port. Very simple to use, you can load any mods (.deh, .bex, .wad, .pk3) in whatever order you want. Files can also be drag-and-dropped externally. Since it's made with ZDoom in mind, the launcher can be resource-intensive at times.   Rocket Launcher - Very simple, lightweight launcher. Supports most types of mods except .deh/.bex files. Allows easy setting of launchgame parameters (-warp to map X, record a demo, no monsters/music) and a handy section for your personal favorite launch settings. Also has native DOSBox support for purists.   Doom Launcher - A counterpart to Quaddicted's Quake Injector. The only popular launcher to track your playtime & WAD stats. Also has integrated idgames archive support, so you can download and play the latest WADs on-the-fly without using a web browser.   Doom Explorer - Easy to use multiplayer server browser, also a great singleplayer launcher. Supports most common source ports and allows use of custom/unknown ports as well. Has the unique feature of being able to search the internet for any WAD name without using a web browser.   There are quite a few other launchers available for multiple operating systems and tailored to many different preferences.     Important info on compatibility options:   Every wad made for vanilla Doom and the majority of Boom wads are NOT meant to be played with jumping and crouching turned on. Conversely, most ZDoom wads or mapsets for other advanced source ports allow for jumping, or may even require it.   For this reason, most non-vanilla ports come with customizable compatibility options. These allow you to make sure you have the right settings for every wad you play, as well as feeling as comfortable as possible in your Dooming experience. If you're unsure what settings to use for a particular wad or mod, simply check out the .txt file which comes included with most Doom content.   Compatibility options for ZDoom-family ports   Compatibility options (complevels) for PrBoom+   If you have any questions, please feel free to ask.   Happy fragging!