There are a great many reasons why software might become abandoned. The useful life of hardware and software is often only a few years. As old hardware and operating systems are replaced with newer and more powerful versions, and new applications are created to take advantage of the improved capabilities (like faster processors, more memory and better graphics), older software eventually becomes obsolete and falls out of use. And after a system upgrade or two, a lot of software becomes incompatible with newer computers and gaming systems, especially if the companies don't work in backward compatibility. To make matters worse, the hardware and software media eventually degrade and stop working.

Game studios and other software producers are also prone to going out of business or getting sold to other companies, so the rights to game titles change hands frequently. Some companies may not even realize they own a particular title, especially if they weren't the originators of the work and it's been off the market for a while.

Another possible reason for abandonment of software is a company deciding that it is no longer commercially viable to spend time and money on advertising, distributing and supporting an old game, or porting it to newer platforms. Heck, even new widely anticipated games sometimes get killed before release to save the studios money.

A copyright owner might intentionally make an older game unavailable to encourage purchase of a sequel (although companies have been known to release older versions as marketing for a sequel, as well). Software might also only be temporarily abandoned, either put out of print to release again later or abandoned for a while before being recreated for a newer operating system or console.

The concept of an orphaned work is similar, although not all abandonware is orphaned. An orphaned work is one where the copyright holder is not known or cannot be located. Some abandonware is orphaned in this manner, but for a lot of it, we know who owns it, but they're no longer distributing or supporting it.

And occasionally, a formerly abandoned software is voluntarily put into the public domain or made publicly accessible by the owner, making it freeware rather than abandonware.

Video games are a multi-billion dollar industry. In 2014, games generated $22 billion in revenue according to the Entertainment Software Association (ESA) [source: ESA]. Software is digital in nature, making it easy to save and distribute online, but like books, movies, songs and other artistic works that can be copied and distributed, software code is subject to copyright laws. Pirating software that's available commercially is clearly illegal and risky, but in the case of abandonware, the ethics and risks become more questionable in a lot of people's eyes, even if the legalities are fairly straightforward.

Technically, any intellectual property that's still under copyright can only legally be reproduced and distributed by the owner, or by anyone granted distribution rights by the owner via a license or other legal agreement. Some aspects of the software, like the name or logo, might also be protected by a trademark.

Copyright lasts a long time, longer than most software has been around. Ever since the Sonny Bono Copyright Term Extension Act of 1998, U.S. copyright for most works (created on or after Jan. 1, 1978) lasts 70 years beyond the life of the author, or, in the case of works created by companies or as works-for-hire, 95 years from publication or 120 years from creation (whichever expires first). Civil penalties for infringement can carry anywhere from a $200 to $150,000 fine per work, or the actual monetary loss to the owner. Possible criminal charges can result in up to five years imprisonment and $250,000 in fines, although a smaller settlement or a cease-and-desist letter have been more common [sources: BSA, Cornell, U.S. Copyright Office].

Even though the time from a software application's release to its relative obsolescence is just a few years, home computer software has only been around for a few decades, so it's essentially all still under copyright, unless the copyright holder has voluntarily put it into the public domain. That means most abandonware is still copyrighted, and a lot of software companies consider it infringement to download and use it.

Both distributing and downloading copyrighted works without permission is considered infringement, so technically if you're getting software from some route other than an authorized source, the owner could come after you or the download site for infringement. It can even be considered infringement if you download a game you have already purchased and still own in another form. Although the Library of Congress did make an exemption to the 1998 Digital Millennium Copyright Act in 2006 to allow users to hack the copy protection on software for computers that are no longer sold or supported for archival purposes, as well as games with copy protection that required physical dongles that could no longer be replaced [sources: Beschizza, Boyes].

Software companies sometimes see old games as competition to their on-the-market games [source: Costikyan]. And companies that don't protect their intellectual property rights when they know infringement is going on actually risk losing some of their rights [sources: Francis, Moby Games]. Industry groups such as the ESA (formerly the Interactive Digital Software Association), and the Software and Information Industry Association (SIIA) try to fight piracy and other copyright infringement of the works of their members. In 1997, when abandonware sites were just starting to come into being (and when the term was coined), these organizations sent cease-and-desist letters to the sites, leading most of them to shut down [sources: Granade, Huthwaite]. However, more abandonware sites sprang up in their place and some of the old sites were resurrected.

The age of abandonware titles and their lack of legitimate availability distinguishes them from what people mean when they talk about pirated games or "warez," which are newer games made available illegally despite still being in print.

Abandonware sites will often remove any software that's disputed by a company, and some will go so far as to place links to the official sites where you can buy the removed game. Some sites will put disclaimers up saying the downloads are only legal for people who own a legitimate copy of the game. They also tend to stick to rules such as only hosting games that are at least several years old and are not available through official channels (as far as they can tell) to distance themselves from pirate sites. Some abandonware sites operate outside of U.S. borders, although U.S. copyright is enforceable in a lot of other countries [sources: Moby Games, Smith].

Advocates for the ability to freely distribute and use abandonware argue that copyright is far too long these days. In 1790, U.S. copyright was 14 years plus one additional period of 14 years if the author renewed, after which the work would fall into the public domain. It has been extended several times since then, and now can potentially last more than 100 years, longer than video games have even existed.

Some fear that if abandoned games do not go out of copyright in a reasonable period, and no one is technically allowed to distribute or download them but the owner, a lot of games will be lost forever, especially given the short shelf-life of computer systems and software and the inevitable degradation of the storage media. For example, in 1996, Polarware (formerly Penguin Software), which produced adventure games in the '80s, released the rights to all their software, but even creator Mark Pelczarski didn't have copies of all of them at that point [source: Moby Games]. Many popular older games whose copyrights are held by existing companies are available for newer platforms, fortunately. But more obscure titles, especially those created by companies that disappeared, run the risk of being lost to time.

Other reasons for making abandonware available include opening it for scholarly study and historical analysis, and for study by game developers who want to improve their skills. Most artists at some point study previous artists' work, and software is a multi-faceted art that includes visual design, music, interactive storytelling and computer science.

And of course, sometimes people just want to relive their favorite games. The very existence and prevalence of abandonware sites point to the fact that there's a market for older games. The popularity of an abandonware title can even give companies information about what titles to re-release. This happened in 1999 when Hasbro released a new version of the 1981 Konami game "Frogger" after noticing that it was still popular. The new version was in the top 10 best-selling games that year [source: Costikyan].

Despite the legal quagmires, lots of sites host abandonware that people download and play. Many post strict rules and attempt to only carry titles that are not available through legitimate means.

As of early 2015, The Official Abandonware Ring (one of the first abandonware-related sites) lists, rates and links to more than 70 websites that host abandonware. Some abandonware sites include Abandonia (now owned by Abovo Media), the Classic Gaming Network and Home of the Underdogs. The latter is dedicated to PC games that were underrated in their time, with some abandonware available on the site and some links to purchase sites for games that are still available commercially.

You can also find abandonware scattered about the Internet on various websites and newsgroups, although as with anything available for free online, you do run the risk of downloading software infected with malware.

Getting games from original media, especially when the hardware that played the media was proprietary, takes programming skills and sometimes special software or hardware. Some games are ripped from the read-only memory (ROM) of old 1970s and '80s game cartridges and converted to binary so that they can be distributed digitally. These game files will often be called ROMs. You will also hear a lot of old floppy-disk and other DOS games referred to as ROMs. Other games are ripped from CD-ROMS (which took off in the 1990s), and these are often called ISOs.

To run the games available on most abandonware sites, you usually need not only the game software, but an emulator or other secondary applications to run out-of-date software, and possibly a license key (sometimes provided by the abandonware site). An emulator is software that mimics the hardware of another machine so that older software can be run on a modern and otherwise incompatible computer.

Hardware emulators exist for various old consoles and computer systems that aren't produced anymore, including DOSBox, VDMSound and Boxer for DOS programs, MAME for arcade games, Stella for Atari 2600, Snes9x for Super Nintendo, Kega Fusion for Sega Genesis, Vice for Commodore 64, ScummVM for old LucasArts games (which were created with the Scumm language) and many more. There are even some emulators for mobile operating systems, but for the iPhone it might require jailbreaking.

You can also find Flash-based recreations or games streamed through browser-based emulators online at various sites. Nesbox is a web-based emulator that lets users upload and play games for NES and Sega systems directly in a browser.

There are even some downright scholarly methods of experiencing older games, as well. "Videotopia" is a collection of playable arcade and home games, hardware and related elements designed to show the evolution of games and computer technology, curated by The Electronics Conservancy. It travels to various museums and science centers. But this means a limited number of people will be able to see it and experience the games.

Another is designed to reach a much wider audience. The Internet Archive is a non-profit organization that collects cultural artifacts and makes them available online as part of their giant digital library for the purposes of preservation and study, including lots and lots of video games. At the time of this writing, they have thousands of games, including hundreds of arcade games and more than 2,600 MS-DOS games that can be played directly online using their own browser-based emulator called EM-DOSBOX.

Sometimes copyright owners decide to release games for free themselves. Companies like Id Software, makers of the popular "Doom" and "Quake" franchises, have been known to release the source code of their older games to the public. Activision, Apogee and Sierra have released old titles as freeware. The company Parallax Software released the source code of their game Descent in 1997. The website Remain in Play hosts a lot of games that have been released by their owners in this way.

And these days, lots of companies are reviving old titles for smartphones and newer gaming consoles, for a price, of course. The 1993 game "Myst" was ported and re-released to smartphones and modern gaming consoles in 2009. Xbox Live Arcade includes lots of classic game downloads, and PlayStation Network includes many of PlayStation's older games.

A number of other companies have made mobile versions of their old games. Activision released an anthology of their Atari 2600 games that includes "Pitfall," "River Raid" and "Kaboom," and released a "Lost Adventures of Infocom" app that allows you to purchase Infocom text based games. Atari has similarly made their games available for smartphones and tablets, including "Centipede," "Asteroids," "Missile Command," "Yar's Revenge" and many others. The games of Bandai Namco ("Pac-Man"), Capcom ("Street Fighter II" and "Ghosts 'n Goblins"), Midway ("Joust," "Defender" and "Rampage"), Sega ("Sonic the Hedgehog") and lots of others are available for mobile devices, as well.

The current owner of Atari lets you play revamped versions of the company's old games online at Atari.com/arcade for free. But if you'd really rather play the original versions with an old-school controller, the Atari Flashback game console was created solely for playing old Atari 2600 games, which are preinstalled in the console (no cartridges required).

GOG.com gets the rights to and sells downloads of older PC and Mac games at reasonable prices. Steam is also a good source to purchase downloads of games you might think are abandonware but are still available for official sale on newer platforms.

And you can, of course, go really old-school and purchase working vintage computers, gaming consoles and games via eBay and other online avenues, or pull them out of your own closet and test them out. A lot of them are still out there for now. But eventually, all old hardware and physical media will go the way of the dodo bird. And when that happens, abandonware or similar sites might be the only way to relive our game-riddled childhoods.