Shareware grew out of the "disk magazine" concept popularized by Softdisk. For the price of a monthly subscription, Softdisk would send you a magazine with a disk or two every month packed with articles and reviews, small applications, utilities and most relevant to our discussion, games. Softdisk made these disk magazines available for most of the popular home computer systems of the day, including the Apple II, Commodore 64 and Macintosh. The IBM disk magazine was called Big Blue Disk, which had its debut in 1986.
Apogee Software, at that time in the person of Scott Miller, began the genesis of the Shareware concept in his Kingdom of Kroz series. He built an engine that relied on ANSI text-based graphics for a game series called Kingdom of Kroz. He published the initial games in this series in Big Blue Disk in the following issues :
Kingdom of Kroz - Issue 20
Dungeons of Kroz - Issue 29
Caverns of Kroz - Issue 35
Return to Kroz - Issue 47
The cover price for the magazine was $9.95, and every few months if you bought the magazine or subscribed to it, another game in the series would be available to you. Eventually, it appears that Miller got tired of distributing through Softdisk and decided to distribute on his own through Apogee. He struck upon the model that the first game in a series should be free (over a BBS) or available at nominal cost (for packaging and media) and the other games should be sold for retail prices. The idea began to bear serious fruit and Apogee replaced Softdisk as the dominant publisher of low-cost PC games.
Eventually Softdisk brought out a game-specific subscription service called Gamer's Edge where the games would be provided by id Software. A three month subscription to this service could be had for $29.99, sixth months for $49.99 and twelve months for $89.99 in 1991 dollars. id Software, consisting primarily of John Carmack, John Romero and Adrian Carmack in the beginning, would fulfill their contract to provide a game every other month for Gamer's Edge as well as develop and release Commander Keen: Invasion of the Vorticons. Keen was released as shareware and published by Apogee.
The shareware aesthetic initially went to the lowest common PC hardware denominator. Early games supported CGA 4-color graphics or 80-column ASCII/ANSI text modes, just like many programs that were simply shared from user to user in the 1980s. In 1990, John Carmack had discovered how to make EGA cards perform pixel-perfect horizontal and vertical scrolling without consuming a ton of CPU time. The EGA hardware was far more advanced than the CGA hardware, even though the resolution stayed the same and the color palette did not increase for most people. When Softdisk did not want to publish Commander Keen for fear of alienating all its CGA customers, id went to Apogee, which was not. EGA was already an old graphics standard, but in 1990 and 1991 it had a mini-renaissance due to games like Commander Keen, Duke Nukem, Crystal Caves, Major Stryker and Catacomb 3-D.
Eventually, the shareware market was dominated by three companies, Apogee Software (later 3D Realms), id Software and Epic MegaGames (later Epic Games), even though id Software was only a developer. id Software is known for its milestones, Commander Keen, Catacomb 3-D, Wolfenstein 3-D, Doom and Quake. Epic MegaGames had the well-known Jill of the Jungle, Jazz Jackrabbit, Epic Pinball and Xargon. Apogee continued with Duke Nukem, Monster Bash and Rise of the Triad. Softdisk hardly bowed out, it continued to publish games in the Dangerous Dave and Catacomb series. Apogee and Epic published some well-known shareware titles like One Must Fall 2097, Tyrian, Raptor and Blake Stone developed by third parties. Even some big box publishers associated with shareware developers, Interplay released Descent despite its status as shareware.
Shareware games are typically broken down into Episodes or Chapters. The first of these was made available "for free" to encourage the player to purchase the full game. This encouraged the established companies to start releasing playable demos of their new games, nothing advertises a game like a free playable sample of the gameplay. Previously, most demonstration programs were just trailers showing gameplay footage running in a loop not unlike the attract mode of an arcade machine. They were usually intended for a PC being displayed by a store. However, whereas the commercial demo usually offered an hors d'oeuvre, a shareware version of a game contained a full episode, a free continental breakfast. When you look at any shareware release, you could typically be guaranteed several hours of playtime, depending on the difficulty of the game. Typically the full game would contain three episodes of roughly equal length. The later episodes would typically be a bit more difficult, maybe a little longer and sometimes offer new enemies, weapons and items.
In the DOS days, almost nothing was specifically for free, there was always a cost for acquisition associated with software. If you purchased a shareware title in a store, you may have had to pay $5.00 because the retailer expected a profit. If you downloaded it over a BBS you typically had to pay long-distance charges. Downloading 1.44MB over a 9600 baud modem takes a lot longer than you think. Services like Prodigy and CompuServe were accessed by fee-subscription only if you were using them to obtain games. If you wanted to send away to the company for a disk, you had to pay shipping and handling. Even if you copied a game from a friend, you were still paying for the disk, which usually ran to $1 per disk in the first half of the 1990s. The shareware versions of the game were freely distributable as far and wide as they could go.
While sometimes the full game could be bought in stores, more frequently you had to purchase the game from the company directly by mail order. In today's world, where 2-day shipping from Amazon is considered good service, having to wait 2-3 weeks for delivery must have been miserable. In the 1980s and 1990s, mail order was a major means of acquiring computer software. Sometimes you could get deals and othertime you had to use mail order because your local Babbages, Electronics Boutique, Software Etc. or Computerland just did not have a copy of that particular game or application in stock.
In the EGA shareware era, platform games dominated. These games were in short supply from the big box retailers and frequently did not compare to games being released for the NES, the dominant home video game device of its day. NES games were very expensive, retailing around $50 and big box PC games were often priced at $50 and sometimes more. By offering a similar product to the NES at a far lower cost, shareware games became sufficiently successful to fund small development houses. However, none of these games had quite the magnificence of Super Mario Bros. 3 or Kirby's Adventure. The NES could display more colors than EGA cards in 200-line modes, but in some games like Commander Keen 4-6 and Keen Dreams, the graphical objects were colorful and well-drawn and animated, making for a lively game.
However, eventually EGA became long in the tooth and everyone had VGA graphics, and developers began to follow suit by almost exclusively supporting VGA only. Around this time, the success of Wolfenstein 3-D meant that more and more shareware games were going to be first person shooters. Wolfenstein and especially DOOM caught the attention of the world to the shareware distribution model. Whether legally or illegally, Wolfenstein and DOOM became nearly ubiquitous. Who doesn't like to kill Nazis with a Chaingun and hear their dying screams? I bet when someone killed Hitler in Episode 3, they may have said something like "Take that you Fascist pig, that's for Auschwitz!" Established companies had to bring out their own first person shooters to compete.
Shareware games frequently pushed technical limits of the hardware they intended to be run on. Big box PC games of the early 90s were typically relying on VGA Mode 13h 320x200 and its single video page. Shareware VGA games used unchained mode to provide for four video pages, tweaked Mode-X-style resolutions like 320x240 and high refresh rates. Most shareware games preferred to work within the hardware capabilities of VGA cards, I cannot think of many that supported SVGA resolutions and color depths. Eventually shareware games like Wolfenstein and DOOM were ported to home consoles with wildly varying degrees of success.
Another issue with shareware games is that they tended to avoid less-common graphics and sound hardware. No shareware game using 16-color graphics supports Tandy Graphics, even though games that did support Tandy and EGA almost always looked identical. If you were looking for support for audio devices other than Adlib like Tandy sound, Game Blaster or even Roland MT-32, look elsewhere. Adlib music quality was frequently first rate compared to strictly retail games which tended to focus more on the dominant MIDI devices of the time, the MT-32 then the Roland Sound Canvas. Games supporting digital sound typically did not support anything beyond the Sound Blaster series and clones at first. Eventually, however, there was some support for the Gravis UltraSound (often buggy) and General MIDI devices.
One hugely important development spurred by shareware was licensing game engines. When id created Wolf3D, they licensed the technology out to Apogee to create Rise of the Triad, Capstone for Corridor 7 and Raven Software for ShadowCaster (published by Origin Systems). Its DOOM engine found even more widespread support and id quickly became known for the quality of its 3D engines. Of course, id had a secret weapon in John Carmack, who understood what was possible with hardware and graphics engines and has continually pushed boundaries for decades. It was rare for big box companies to license their technology to its competitors, but eventually many of them would license the engines from id and Epic (Unreal) for their games. One positive aspect from the shareware era was the policy of companies like id Software to release the source code to their hardware engines to allow others to make source ports of these games and design custom maps. Many shareware games from this era have been made freeware compared to big box companies that will sit on their decades-old IPs.
Quake was the last great shareware game. It may have been too successful because with the shareware release you could play multiplayer as you liked with anyone else. DOOM had begun the process of players making custom multiplayer maps, but it was Quake where things began to explode. Quake offered easy internet multiplayer through QuakeWorld, which was a Windows 95 executable with support for TCP/IP multiplayer. It is no accident that Quake II and its successors were distributed on a strictly demo/retail basis. However, where shareware began by catering to users or lower-end hardware, DOOM and Quake required 486s and Pentiums for any real playability, and those CPUs were still new and expensive at the time of those games' releases.
Windows 95 foretold of the impending doom of the shareware model. Shareware games had to compete with a platform that was far more friendly to cheap, casual games than DOS ever was. In addition, Windows games frequently came on multiple CDs and ran to hundreds of megabytes in size. Most commercial versions of shareware games were not copy protected and were frequently pirated. Development costs had skyrocketed for quality products, as had support obligations to match. In the end, the successful companies like id became a big developer with Quake II-4 and DOOM 3 and Epic a big publisher with its Unreal and Unreal Tournament series.
The closest thing to shareware today in terms of its distribution is the chapter/seasons releases from companies like Telltale Games. In the Telltale Games commercial model, a complete story in a game was released as chapters or episodes over the course of several months. One some platforms, now mainly mobile, you could usually obtain the first episode for free and then decide if you wanted to pay for later episodes. If you knew you wanted the full game, you could buy a full season pass and receive chapters automatically as they were released. On PC platforms, typically the season pass was the only option available and you just have to wait for the next episodes to be released.