Correction Appended

Halo 3 and Oblivion haven’t been available in that format yet.

There is little incentive to download a game rather than buy a tangible disc: it is rarely cheaper to download. Downloadable versions of best-selling PC games like Unreal Tournament III and BioShock cost the same as the discs.

For people who like playing video games, whether they are hard-core players or occasional dabblers, downloading won’t be the main way to procure games. But online delivery is becoming very handy for the players who want to build quickly on the experience they had in a favorite game like the shooter Halo 3 or the role-playing adventure Oblivion. It will also be useful for those who want to relive an experience of a favorite game played a generation ago, like Pac-Man or King’s Quest.

Here are a few ways to get the most out of downloads.

PC GAMING The leading downloadable PC game distributors are Valve Software and GameTap. Both offer full-size games to download to a gamer’s hard drive. GameTap also offers smaller titles meant to appeal to a broader audience than the hard-core gamers Valve’s lineup serves.

Valve charges per game, with big-hit titles like Call of Duty 4: Modern Warfare and BioShock priced at $49.95 (Circuit City’s price for each is typically $49.99). GameTap offers two all-you-can-download subscription options, $9.95 a month or $59.95 a year, for access to its library of nearly 1,000 titles. About 50 titles are free to anyone who registers with the site. GameTap also allows people who are not subscribers to download games at prices closer to those of the retail editions.

While GameTap recently began offering Mac games, Valve is strictly for Windows users.

Both services provide system requirements and recommended specifications for any given game so you do not download a game your computer cannot run.

My download from GameTap of Lara Croft Tomb Raider: Anniversary, a 1.1-gigabyte Windows game that was available in stores and on GameTap the same day, took about 45 minutes to complete over my cable broadband connection.

I downloaded from Valve the highly acclaimed thinking man’s first-person shooter, Half-Life 2, ($19.95 on Valve, and $19.99 at a nearby Target store) in about half an hour despite its relatively compact 900 megabytes.

Both games played exactly as they would if I had installed them from discs.

But those pieces of plastic can be reassuring. If the computer is damaged, the discs would be handy to reinstall on a repaired or new computer.

But a similar safety net can come with downloaded games. A GameTap subscription allows games to be redownloaded anytime, and up to two computers in a household can run the games at the same time. Valve and other smaller download services like GameStop, IGN and EB Games grant buyers activation codes that can be used on one or more machine. The downloaded game can also be deactivated on one PC and then reactivated on another. If a Valve game bites the dust because of a crash, the registered owner can redownload and reinstall the title and jump right back into the game.

Both services offer online forums for discussing games and swapping tips, though Valve goes further by offering a feature for meeting game-playing friends that also tracks statistics and helps to schedule group events.

Many hard-core PC gamers eagerly seek free modifications, or “mods,” of popular games. Mods are created by dedicated players and programmers, usually with no connection to the company that created the game. The software adds new content like weapons, characters, scenarios and multiplayer maps. Mods hav
e been written for some of the most popular PC games, including Half-Life 2, Gears of War, Enemy Territory: Quake Wars and Unreal Tournament. Gamers say that some of the best sites for downloading mods are fileplanet.com, gamespot.com, gamespy.com, fileshack.com and filefront.com.

VIDEO GAME CONSOLES The makers of the game consoles, like Xbox 360, PlayStation 3 and Wii, want you to buy discs for new releases, even though all the machines have Internet connections and PlayStation 3 has a built-in hard drive like a PC. But they do encourage gamers to download old games. Microsoft’s Xbox Live Marketplace for Xbox 360 gamers offers more than 100 “arcade” titles like Uno, Ms. Pac-Man and Frogger, as well as add-on content for the latest titles like the Halo 3 Heroic Map Pack and new songs for the music game Rock Band. (Indeed, no discs are available for some Halo 3 expansion packs; they can only be downloaded.) The company also sells several “Xbox Classics,” the titles that ran on the 360’s predecessor, the original Xbox. Unfortunately, to buy any of them, Microsoft forces gamers to use an annoying points system that converts $1 to 80 points.

Sony’s PlayStation Store for the PlayStation 3 takes players down a similar retro game memory lane. It sells games that played on the original PlayStation. Several of the titles can be played on either the PlayStation 3 console or downloaded from the PS3 to Sony’s PlayStation Portable hand-held game device and played on that. (And like the PC game download business, previously purchased games and add-ons can be redownloaded in the event of a console crash or accidental deletion.)

The biggest retro download store belongs to Nintendo, the maker of the Wii. Its Virtual Console feature offers downloadable games created for the original Nintendo Entertainment System as well as the subsequent Super Nintendo and Nintendo 64 consoles. Donkey Kong, Super Mario Brothers and Pac-Man can be found there. The store also sells games that were first released for Nintendo competitors like the TurboGrafx, the Neo Geo and the Sega Genesis.

Although games cannot be transferred to the Nintendo DS hand-held game system, Nintendo recently announced that it would soon offer DS demos to be downloaded to the hand-held’s main memory and playable until the device is powered off, at which point they disappear.

But don’t expect the old-fashioned game discs to disappear so easily.