Key features
- Vulkan, OpenGL & software renderers — runs on almost anything.
- ZScript modding — the most powerful Doom mod scripting available.
- Huge mod compatibility — the target engine for most modern mods.
- True 3D-style geometry — slopes, 3D floors, dynamic lights.
- Built-in launcher — pick your IWAD and load mods without the command line.
- Multi-game — Doom, Doom II, Heretic, Hexen, Strife & Chex Quest.
- Quicksave anywhere + autosaves and full options menus.
- Free & open-source — GPL-licensed, no cost, no ads.
What is GZDoom?
GZDoom is the most widely used source port for the classic Doom engine. A source port is a modernized version of the original game’s code that lets decades-old games like Doom (1993) run natively on current operating systems, in high resolutions, with modern controls — while staying faithful to how the games actually played.
It descends from a long lineage: id Software released the Doom source code in 1997, which led to ZDoom, and GZDoom is the OpenGL/Vulkan-rendering branch of ZDoom that became the de facto standard. Where the original engine was limited to flat levels and software rendering, GZDoom adds true 3D-style geometry (slopes, 3D floors), dynamic lighting, and a full scripting language, ZScript, that modern mods are built on.
If you want to play almost any Doom mod made today — from subtle gameplay tweaks to total conversions — GZDoom is the port to install first. Its multiplayer-focused cousin Zandronum shares the same Skulltag-era lineage and is the choice for online play; we cover that trade-off below.
How to install GZDoom
// From zero to playing — step by stepDownload the port from the official source
Grab the latest build from zdoom.org (see the download box). Unzip it anywhere — GZDoom is portable and doesn’t need an installer.
Get an IWAD (the game data)
GZDoom is just the engine — it needs a game file called an IWAD (e.g. doom2.wad). Own Doom on Steam or GOG? Copy the WAD from your game folder. Don’t own it? Use Freedoom, a free, license-clean IWAD.
Run GZDoom & pick your game
Launch gzdoom.exe. Drop your IWAD next to it (or point the launcher at it) and GZDoom lists every game it finds. Select one and you’re in.
Load a mod
Drag any .pk3 or .wad mod onto gzdoom.exe, or add it in the launcher’s file list. That’s it.
GZDoom system requirements
GZDoom vs other source ports
Need to pick between ports?
Short version: GZDoom handles most needs. For the full head-to-head and our ranked list, see the dedicated pages.
Frequently asked questions
Is GZDoom free?
Yes. GZDoom is free and open-source software, released under the GPL. There is no cost, no trial, and no ads. You only need to legally own a game IWAD (or use the free Freedoom) to play.
Is GZDoom safe to download?
Yes, when you download it from the official source (zdoom.org or the official GitHub releases). It is open-source, so the code is publicly auditable. Avoid third-party mirrors — we link only to the official source, and we host no binaries ourselves.
Do I need the original Doom to play?
You need a Doom-engine IWAD. If you own Doom or Doom II (Steam, GOG, or the original discs) you already have it. If not, Freedoom is a free, legal, GZDoom-compatible replacement that gives you full levels to play.
GZDoom vs Zandronum — which should I install?
GZDoom for single-player and the latest mods; Zandronum for online multiplayer. They share a lineage but have diverged: GZDoom tracks bleeding-edge ZScript; Zandronum prioritises stable netcode.
Sources
- EXT Official GZDoom site zdoom.org
- EXT GZDoom on GitHub github.com
- EXT ZDoom Wiki — GZDoom zdoom.org