Data files for the original Doom 3, including the MD5 hash:

MD5 (base/pak000.pk4) = 71b8d37b2444d3d86a36fd61783844fe
MD5 (base/pak001.pk4) = 4bc4f3ba04ec2b4f4837be40e840a3c1
MD5 (base/pak002.pk4) = fa84069e9642ad9aa4b49624150cc345
MD5 (base/pak003.pk4) = f22d8464997924e4913e467e7d62d5fe
MD5 (base/pak004.pk4) = 38561a3c73f93f2e6fd31abf1d4e9102
MD5 (base/pak005.pk4) = 2afd4ece27d36393b7538d55a345b90d
MD5 (base/pak006.pk4) = a6e7003fa9dcc75073dc02b56399b370
MD5 (base/pak007.pk4) = 6319f086f930ec1618ab09b4c20c268c
MD5 (base/pak008.pk4) = 28750b7841de9453eb335bad6841a2a5

And if you own the expansion pack Resurrection of Evil:

MD5 (d3xp/pak000.pk4) = a883fef0fd10aadeb73d34c462ff865d
MD5 (d3xp/pak001.pk4) = 06fc9be965e345587064056bf22236d2

Note that you have to patch your game to version v1.3.1 to obtain all files.

If you bought the game on CDs/DVD, base/pak000.pk4 - pak004.pk4 and d3xp/pak000.pk4 can be found on the disks, the other files are from the patch. If you bought it on Steam it should already be fully patched.

On Linux (and probably other Unix-like systems and maybe even Windows with a mingw shell) you can extract the needed files from the official 1.3.1 patch for Linux with:

sh /path/to/doom3-linux-1.3.1.1304.x86.run --tar xvf --wildcards base/pak* d3xp/pak*

First you need to buy the game (and the Resurrection of Evil Addon, if you want that too), of course.

On Windows, just install it and copy the game data from there (see above for what files are needed).

On Linux, the process is the same, but since the game is Windows-only on Steam, you may need to change a setting before Steam will let you install it. Open the Steam settings, go to the "Steam Play" section, and make sure "Enable Steam Play for all titles" is checked. Then, simply proceed as you would on Windows. (Note that changing this setting will enable all Windows titles to be downloaded, not just Doom 3, so you might want to disable it after it's finished downloading to avoid confusion.)

On macOS, Steam Play is not available, so unfortunately you can't just install the game. However, you can still download the game with SteamCMD.
this description on how to install SteamCMD on your system. You won't have to create a new user.

Then you can download doom3 with

./steamcmd.sh +@sSteamCmdForcePlatformType windows +login <YOUR_STEAM_LOGIN_NAME> +force_install_dir ./doom3/ +app_update 9050 validate +quit

(replace <YOUR_STEAM_LOGIN_NAME> with your steam login name)
When it's done you should have the normal windows installation of doom3 in ./doom3/ and the needed files in ./doom3/base/
It should be possible to get the Resurection of Evil data in the same way, by replacing 9050 with 9070.
That number is the "AppID" of Doom3/RoE; if you wanna use this to get the data of other games you own, you can look up the AppID at https://steamdb.info/

No. Doom 3 BFG uses different formats for the archives and the game data itself.
Try RBDoom3BFG.

Each mod keeps its data files in its own sub directory relative to the so called BASEPATH. For the original game the sub directory is named base and the expansion is named d3xp.

dhewm 3 tries to find the BASEPATH in the following order:

For Windows:

• Next to the binary dhewm3.exe
• The original Doom 3 installation directory (if you have installed the game from CD)
• The steam Doom 3 installation directory

For *nix:

• The data directory which was configured at compile time ($CMAKE_INSTALL_PREFIX/share/dhewm3; the default is /usr/local/share/dhewm3)
• Next to the binary dhewm3
• The default Doom 3 installation directory /usr/local/games/doom3 (if you have installed the game from CD)

For OSX:

• The directory the bundle is in

You can also tell dhewm3 which folder to use as basepath with the fs_basepath commandline option, like
./dhewm3 +set fs_basepath /home/HansWerner/Games/doom3

Data files can also be placed in the savegame folder (see below). These will always take precedence over the paths listed above on all platforms.

For Windows:

• My Games\dhewm3 in your localized My Documents

For *nix:

• config files: $XDG_CONFIG_HOME/dhewm3 (default: $HOME/.config/dhewm3)
• savegames and dhewm3log.txt: $XDG_DATA_HOME/dhewm3 (default: $HOME/.local/share/dhewm3)

For OSX:

• Library/Application Support/dhewm3 in your home directory

This isn't tested much, but seems to work. Just copy them to the right folders (see question right above this one).

• On Linux you can find the old Savegames in $HOME/.doom3/base/savegames/ (or d3xp or some mod name instead of base), so copy the savegame folder to $XDG_DATA_HOME/dhewm3/base/
• On Windows the savegames are in the installation directory (for example Doom 3\base\savegames\). Move the savegames folder to My Documents\My Games\dhewm3\base\.

This is a side effect of the move to SDL.

You can just open it by pressing Shift and Escape at the same time.

Or you start the game once with the command line parameter: +set in_kbd german and open it with the key below Escape (^ on German layout, ~ on US layout, etc)

Current supported layouts are: english french german italian spanish turkish

If your layout is not supported, file a bug. You need to mention the symbol codes of the console key for your keyboard layout. These can be taken from this codepage. We need the codes (the bold ones) for the symbol you get when pressing that key, once without and once with shift.

Just enable EAX 4.0 HD in the system options.

Yes, but only in dhewm3 1.5.1pre1 and newer.

Not really.
It doesn't seem to work at all on Raspberry Pi 3 and older (you might get it to display the main menu but it will crash once you try to start the actual game).
It does work on Raspberry Pi 4 (at least the 4GB version, I haven't tested others) but the performance is really poor.

This problem so far has only be observed with Chromebooks, I could imagine it happening on other ARM based devices as well, even though I couldn't figure out why exactly it happens (see https://github.com/dhewm/dhewm3/issues/102). It seems to hang while showing "loading menu".
Anyway, the workaround is to start the game with ./dhewm3 +set in_tty 0

UPDATE: This bug is fixed in dhewm3 1.5.0 and newer.

... and the backtrace shows something about libogg/libvorbis.
This is a bug in libvorbisfile3 1.3.4-2 and earlier in debian (and possibly derived Distros like Ubuntu), caused by a patch that debian applied.
See https://github.com/dhewm/dhewm3/issues/104 and https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=782831
Try updating libvorbisfile or building and launching with a fixed version as described below:

On Ubuntu Wily, you can a tarball of libvorbis 1.3.4 source from its launchpad page, and then build with something like:

tar xvf libvorbis-1.3.4.tar.gz
cd libvorbis-1.3.4
./configure
make
sudo make install

To use the fixed version instead Wily's version, set your LD_LIBRARY_PATH when launching dhewm3:

LD_LIBRARY_PATH=/usr/local/lib dhewm3

dhewm3 was started by the amazing dhewg, who did all of the hard work of porting Doom3 to SDL, OpenAL and to be 64bit-compatible.
So "dhewm3" is a contraction of "dhewg's Doom3".