Write-ups provided by Decay and Keyboard Doomer.
Ports: How and where am I playing?
Download all the ports and determine which one you like best. Each port has a series of compatibility flags (compatflags) to more closely emulate vanilla Doom. Enable those (or not) and see how you like it. Make your own decision on what port you like, or play them all.
There are currently three primary multiplayer source ports. They are Odamex, Zandronum, and ZDaemon. You may see other ports referred to in multiplayer contexts such as Chocolate Doom, or GzDoom, but outside of individually set-up games, they are not used by 99% of the playerbase. It is best to ignore them (for multiplayer purposes) and focus on the three previously mentioned.
Zandronum has the most updated ZDoom code base, allowing for huge flexibility in game modes and features. Zandronum’s greatest strength lies in the ability to support mods, not just maps, though it definitely lends itself to new avenues of mapping given the availability of 3D floors and extensive ACS support that can really spice up game play. If you want to make radical designs and game play, Zan is the port for you. But that doesn’t mean you can’t make relatively oldschool style maps with a small twist.
ZDaemon is targeted more towards audience preferring “old school” Doom. However, while it doesn’t support some modern features like DECORATE, UDMF or PK3 files, you can get decent use of its ACS support and will find many mods that make use of it. ZDaemon is based on ZDoom 1.23b so it supports most features of ZDoom (Doom in Hexen) and Boom formats. Besides that it offers great demo support that you can rely on not getting broken in the next major version, unique “picture in picture” view for duels that allows you to spectate both players at once, active development and welcoming community.Odamex, from a mapping standard, supports the least amount of features. It is based on (I believe) CSDoom and draws on an additional ZDoom 1.22 version. While it supports ZDoom (Doom in Hexen) mapping formats, it does not support ALL the features it offers. There may also be discrepancies between what is supported properly online and offline. Wads played are more “classic” in the sense that they do not require any special features. Complex wads requiring scripts, DECORATE, certain actor types, and mods are unsupported. IMPORTANT: Does not support UDMF formats, pk3 files.
Odamex has 2 great features which other ports do not that make it stand out from a mapping standpoint. First would be on-the-fly wad-switching, which allows servers to host multiple wads without them overlapping each other. This is beneficial for map naming conflicts, texture override priorities, and palette issues. Second great feature is a true-colour software renderer.