Steam

Every official Doom game and various other commercial games based on the Doom and Doom 3 engines have been released on Valve's content delivery system Steam. Most of the games were made available on August 03, 2007.

On Steam, classic Doom games and other games that use the Doom engine by default run under the DOSBox emulator, but it is also possible to use source ports with the games. More information on this below.

Classic Doom games

 * The Ultimate Doom ($9.99 / 9,99€ / £5.99)
 * Doom II ($9.99 / 9,99€ / £5.99)

Doom engine games

 * Heretic: Shadow of the Serpent Riders ($4.99 / 4,99€ / £2.99)
 * Hexen ($4.99 / 4,99€ / £2.99)
 * Hexen: Deathkings of the Dark Citadel ($4.99 / 4,99€ / £2.99)
 * Note: Contrarily to all other Doom-engine games available on Steam, this version of Deathkings is not the latest and requires the to work correctly.

Doom 3
Note: Ownership of the normal Doom 3 on Steam (no longer sold) gives a 33% discount when buying the BFG edition.
 * Doom 3: BFG Edition ($29.99 / 29,99€ / £19.99)

Doom 3 engine games

 * Quake 4 ($19.99 / 19,99€ / £14.99)
 * Prey ($14.99 / 14,99€ / £8.99) (not available in the UK, but can be activated via retail CD key)
 * Enemy Territory: Quake Wars ($14.99 / 19,99€ / £14.99)
 * Wolfenstein ($29.99 / 19,99€ / £9.99)
 * Brink ($19.99 / 19,99€ / £14.99)

Collections

 * Heretic + Hexen Collection ($9.99 / 9.99€ / £5.99)

How to use source ports with games downloaded from Steam
Some source ports, such as Chocolate Doom or ZDoom, look if a Steam folder is present and will search it for the game IWADs. The following steps are therefore not necessary with some ports.

First, download the archive that contains the source port executable and other files necessary to run it. Then decompress the source port archive, and put all the files/folders into the folder \SteamApps\Common\\base. Running the source port main executable (for example, zdoom.exe or prboom.exe) should then start the game.

Alternatively, the IWAD (named doom2.wad for Doom II, hexen.wad for Hexen, etc.) can be copied from \SteamApps\Common\\base to a directory of your choosing and the source port files decompressed/copied there. Again, running the source port main executable should then start the game.

If you wish to run the games with a source port via Steam or its shortcuts, you need to decompress and copy the source port files to <Steam directory>\SteamApps\Common\<game name>\base</tt> as instructed above. Then you need to rename or delete dosbox.exe</tt> and rename the port's executable to dosbox.exe</tt>. After this the Steam shortcut will launch the game via the chosen source port. Steam's overlay will work with hardware accelerated ports, and Steam Cloud support for synchronizing saves between PCs will continue to work as long as the port uses the .dsg</tt> extension for its saves.