i did some research and have to correct myself about some things:
1. copyright expires according to law of a respective country (that means DO is still copyrighted)
2. abandonware is a blurry term and neither legal nor illegal
3. some publishers actually declare stuff freeware
e.g. in france, software is protected for 70 years after release
that implies that abandonware sites hosted in france (and at least two of them offer DO for download) have to ask permission before having a title for download and usually do so. therefore, DO must be freeware since it is available on so many sites hosted in the US or european countries. my guess is that EA authorized those sites but that doesnt mean everybody can offer it for download. it is up to the admin of this website to try and get permission - i think it should be an easy task since the site is really good and EA might like it. definitely worth a try.
last but not least a list of freeware/formerly commercial games (source: wikipedia)
3 in Three (1989),
a puzzle game for Mac OS by Cliff Johnson
Abe Lincoln Must Die! (2007),
the fourth part in the Sam & Max episodic series by Telltale Games, released as freeware on November 5, 2007.
Abuse (1996), a side-scrolling shooter.
Adventureland (1978), an adventure game by Scott Adams.
The Adventures of Maddog Williams in the Dungeons of Duridian (1992),
an adventure game for Atari ST and PC by Game Crafters
The Adventures of Robby Roto! (1981),
an arcade game by Bally Midway.
Akalabeth (1979), a.k.a "Ultima 0",
a role-playing game by Richard Garriott.
Alien Carnage (1994),
a.k.a Halloween Harry, a side-scrolling platform game published by Apogee Software.
Allegiance (2000),
a multiplayer space shooter / RTS by Microsoft Research.
Anacreon: Reconstruction 4021 (1987),
a strategy dos game by George Moromisato.
Antheads: It Came from the Desert 2 (1990)
is a adventure game expansion pack to It Came from the Desert released as freeware by the author Cinemaware.
Arctic Adventure (1991),
a platform game by Apogee Software, re-released as freeware on March 2009.
Area 51 (2005),
a first person shooter by Midway Games. Its free release was sponsored by the US Air Force.
At the Carnival (1989),
puzzle game for Apple Macintosh and MS-DOS by Cliff Johnson
Battle Chess (1988),
declared freeware in 1994 to celebrate the success of its successor, Battle Chess II.
Battlecruiser 3000AD (1996),
a space simulator by Derek Smart.
Battlecruiser Millennium (2003),
a space simulator by Derek Smart.
BC Kid (1992),
a platform game by Factor 5.
BC Racers (1993),
a racing game by Core Design.
Beneath a Steel Sky (1994),
an adventure game by Revolution Software, released to support the ScummVM Project.
Beyond the Titanic (1986),
a text adventure game by Apogee Software, re-released as freeware in March 1998.
Beyond Castle Wolfenstein (1984),
a stealth game by Muse Software
Bio Menace (1993),
a side-scrolling platform game by Apogee Software, released as freeware in December 2005.
Blades of Exile (1997),
a role-playing game for Apple Macintosh and Windows by Jeff Vogel of Spiderweb Software.
Boppin' (1994),
a puzzle game published by Apogee Software, released as freeware in 2005.
Castle of the Winds (1989),
a tile-based RPG for Windows 3.x, written by SaadaSoft.
Castle Infinity (1996),
an MMOG by Starwave.
Caves of Thor (1989),
a maze game by Apogee Software.
Championship Manager: Season 01/02 (2001)
a soccer management game by Sports Interactive and Eidos
Clonk Endeavour (2004),
an action strategy game by RedWolf Design released as freeware on 19 May 2008.
Clyde's Adventure (1992),
a platform game DOS game by Moonlite Software.
Clyde's Revenge (1995),
a platform game DOS game by Moonlite Software.
Command & Conquer (1995),
a real-time strategy game by Westwood Studios.
Command & Conquer: Red Alert (1996),
a real-time strategy game by Westwood Studios. Made freeware in 2008 to promote the release of Command & Conquer: Red Alert 3.[1]
Cybersphere (1996),
arcade game for DOS and Amiga by Clay Hellman.
Dark Ages (1991),
a platform game by Apogee Software. Re-released as freeware on March 2009.
Dark Sun: Shattered Lands (1993),
a computer role-playing game by SSI available on the "Dark Sun Online: The Age of Heroes" site, which is an unfinished remake of the original Dark Sun Online: Crimson Sands.
Dark Sun: Wake of the Ravager (1993),
a computer role-playing game by SSI available on the "Dark Sun Online: The Age of Heroes" site, which is an unfinished remake of the original Dark Sun Online: Crimson Sands.
Defender of the Crown (1986),
a strategy game by Cinemaware.
Dink Smallwood (1997),
an RPG by RTsoft, released as freeware on 17 October 1999.
The Elder Scrolls: Arena (1994),
a role-playing game by Bethesda Softworks, floppy disk version released as freeware in 2004 to mark the 10th anniversary of the TES series, and as publicity release prior to the 4th installment, Oblivion.
The Elder Scrolls II: Daggerfall (1996),
a role-playing game by Bethesda Softworks and sequel to the aforementioned Arena, was released as freeware on July 9, 2009, to mark the 15th anniversary of the TES series.
Elite (1984),
space trading game by Acornsoft, freeware release in 1999 courtesy of game developer Ian Bell.
Elite + (1991),
space trading game by Acornsoft, freeware release in 1999 courtesy of game developer Ian Bell.
Enemy Nations (1997),
a real-time strategy by Windward Studios.
F.E.A.R. Combat (2006),
the multiplayer portion of F.E.A.R., by Monolith Productions.
Fish Fillets (1998),
a puzzle game by Altar Games which was released under the GPL in 2002. Subsequently the Fish Fillets NG project has recoded the engine to enable multi-platform release.
Flight of the Amazon Queen (1995),
an adventure game by Interactive Binary Illusions, released to support the ScummVM Project.
The Fool's Errand (1987),
a puzzle game by Cliff Johnson
Full Spectrum Warrior (2004),
a tactical shooter by Pandemic Studios released as a free ad-supported download as of September 29, 2008.
Glider and Glider PRO.
God of Thunder,
a puzzle game by Adept Software.
Grand Theft Auto (1998),
by Rockstar Games, released as registerware freeware.
Grand Theft Auto 2 (1999),
by Rockstar Games, released as registerware freeware.
Gridlee (1983)
is an arcade game by Videa.
Ground Control (2000),
a futuristic real-time tactics game produced by Massive Entertainment, registerware freeware released on July 1, 2004 to serve as promotion for its sequel, Ground Control II: Operation Exodus.
Hardwired (a pre-release version of Red Zone) (1994),
a shooter by Zyrinx for the Sega Mega Drive/Genesis.
Heros: The Sanguine Seven (1993)
released free by the author in 2005.
Hidden and Dangerous Deluxe (1999),
a game by Illusion Softworks, released as freeware to serve as promotion for its sequel, Hidden & Dangerous 2.
Hitchhiker's Guide to the Galaxy (1984),
a game by Infocom, made publicly available as a web-based game by the BBC.
Infantry (1999),
a 2D MMORPG similar to PlanetSide. Released as freeware in 2007.
Iron Seed (1994),
a real-time strategy game released as freeware by the author to promote Iron Seed 2.
It Came From The Desert (1989),
an adventure game released as freeware by the author Cinemaware.
Jetpack (1993),
a platform game by Adept Software.
Katakis (1987),
an Amiga side-scrolling shoot-em-up arcade game by Factor 5.
Ken's Labyrinth (1993),
a first-person shooter by Ken Silverman.
Kiloblaster (1992),
a game by Epic MegaGames, released as freeware on 4 August 2008.
King of Chicago (1987),
an action, adventure, and strategy game by Cinemaware.
Kroz (1987),
an action game by Apogee Software. Re-released as freeware on March 2009.
Kye (1992),
a puzzle game by Colin Garbutt.
Lode Runner Online: Mad Monks' Revenge,
a side-scrolling arcade game by Sierra Entertainment, based on the concept presented by the classic game Lode Runner (malfunctions on Win2000, WinXP and greater).
Lure of the Temptress (1992),
an adventure game by Revolution Software.
Mad TV (1991),
a management simulation game by Rainbow Arts.
Major Stryker (1993),
a scrolling-shooter game by Apogee Software, released as freeware on March 2006.
Marathon Trilogy,
a series of first-person shooters by Bungie.
Monuments of Mars (1990),
a platform game by Apogee Software. Re-released as freeware on March 2009.
Mechwarrior 4 (2000)
has been announced to soon be released as freeware by battletech.com to commemorate the Battletech series' 25th anniversary.
No Gravity (1998),
a Space combat simulator game by Realtech VR.
One Must Fall: 2097 (1994),
a fighting game by Diversions Entertainment, declared freeware on February 10, 1999.
onEscapee (1997),
an action-adventure game by Invictus Games, Ltd., released as freeware on January 26, 2006.
Pharaoh's Tomb (1990),
a platform game by Apogee Software. Re-released as freeware on March 2009.
Purge (video game) (2003),
a Windows online first-person shooter game by Freeform Interactive.
Railroad Tycoon Deluxe (1993),
a business simulator by MicroProse.
Riftspace (2000)
by Starwraith 3D Games, a space mercenary simulation built after the ideologies of Elite.
Rise and Fall: Civilizations at War (2006),
a real-time strategy/third-person shooter by Stainless Steel Studios and Midway Games. Re-released as ad-supported freeware, sponsored by the US Air Force.
Rocket Ranger (1988),
action game by Cinemaware
R-Type (1987),
a side-scrolling shoot-em-up arcade game. The Amiga version (1989) is freely downloadable at Factor 5's website.
Savage: The Battle for Newerth (2004),
a blend of FPS and RTS gameplay by S2 Games.
Savage 2: A Tortured Soul (2008),
the sequel to Savage: The Battle for Newerth, re-released as freeware December 9, 2008.
S.D.I (1987),
an action adventure game by Cinemaware.
Shadowbane (2003),
a fantasy MMORPG by Ubisoft, released as freeware in 2006.
SimCity (1989),
a City-building game, was released under the GPLv3 for the One Laptop per Child project, and as Micropolis to the general public (the original title of the game).
SkyRoads (1993),
a platform puzzle game by Bluemoon Interactive.
Spheres of Chaos (1992),
a shooter game by Iain McLeod, released as freeware in October 2007.
Star Control II (1992),
an adventure/action game mix released under the GPL by Toys For Bob under its subtitle The Ur-Quan Masters ten years later.
Stargunner (1996)
is a scrolling shooter by Apogee Software, released as freeware in 2005.
Starsiege: Tribes (1998),
a first-person shooter by Dynamix/Sierra On-Line, released as freeware in May 2004 as publicity for the release of Tribes: Vengeance.
Star Wraith II (2000)
by Starwraith 3D Games, a space military simulation game, released as freeware as a publicity stunt for its successor, Star Wraith III: Shadows of Orion.
Star Wraith III: Shadows of Orion (2000)
by Starwraith 3D Games, a space military simulation featuring multiplayer capabilities.
Star Wraith IV: Reviction (2000)
by Starwraith 3D Games, the sequel to Star Wraith III and has a similar concept.
SubSpace (1997),
a 2D top-down space shooter game with massive multiplayer capabilities originally released by Virgin Interactive
The Suffering (2005),
an horror third/first person shooter developed by Surreal Software and published by Midway Games. It has been released free but ad-supported in September 2008.
Supaplex (1991),
a Boulder Dash-like puzzle game by Michael Stopp and Philip Jespersen.
Supernova (1987)
is a text adventure game by Apogee Software, re-released as freeware in March 1998.
Super ZZT (1992)
is a MS-DOS game by Tim Sweeney and Allen Pilgrim.
S.W.I.N.E. (2001),
a real-time tactics game by StormRegion, released as freeware (S.W.I.N.E. Free Christmas Edition) in 2005.
Telengard (1982),
dungeon crawl computer game by Daniel Lawrence.
TerraFire (1997),
action game computer game by ORT Software.
Titans of Steel: Warring Suns (2003),
a Battletech-style turn based strategy game released free on February 14, 2008.
Traffic Department 2192 (1994),
a top-down shooter by Epic MegaGames, released as freeware by its author, John Pallett-Plowright, in 2007.
Treasure Island Dizzy (1987),
a puzzle game by Oliver twins.
Tribes 2 (2001),
a first-person shooter by Dynamix/Sierra On-Line, free download release in 2004 as publicity for the release of Tribes: Vengeance.
Trivia Whiz (1988),
a trivia game by Apogee Software.
Turboraketti II (1993),
an Amiga cavern-flying game by Heikki Kosola.
Tyrian/Tyrian 2.0/Tyrian 2000 (1995, 1996, 1999),
a space shooter by Epic MegaGames, released as freeware by its author, Jason Emery, in 2004.
Universal Combat (2004),
a space simulator by Derek Smart, released as freeware on January 2, 2008.
Vantage Master Online (1998),
a tactical RPG by Nihon Falcom, released as freeware in 2002.
Wild Metal Country (1999),
by Rockstar Games, released as registerware freeware in 2004.
Wings (1990),
a flying game by Cinemaware.
Wings (1996),
a cavern-flying game by Miika Virpioja.
Word Whiz (1988),
a trivia game by Apogee Software.
Xargon (1993),
a platform game by Epic MegaGames, released as freeware on 4 August 2008.
Xenophage: Alien Bloodsport (1995),
a fighting game by Argo Games/Apogee Software, released as freeware in 2006.
Zero Tolerance (1994),
a Sega Mega Drive/Genesis first person shooter game by Technopop.
ZZT (1991)
by Epic Megagames.
unfortunately, Dark Omen is not in that list but it might just be incomplete