Although a comprehensive list of all the roguelikes would likely strain the patience of most readers, it's worthwhile to mention at least a few of the most influential: Moria, Hack, Larn, and Ancient Domains of Mystery. Moria, as the name implies, is themed on J. R. R. Tolkien's literary work, The Lord of the Rings, and debuted in 1983.
The original version was authored by Robert Koeneke, a student at the University of Oklahoma. Unlike the original Rogue, Moria has a persistent town with six shops where players can buy equipment.
Another popular and more recent roguelike named Angband is ultimately derived from this game. Hack, which first debuted in 1982, was authored by Jay Fenlason and three friends. Hack was noted for its clever interaction with the gameworld and its creatures. Slaying and then eating a leprechaun, for instance, will teleport the character to a random location.
This game became the basis for NetHack, a 1987 game that was one of the earliest to utilize the Internet in its development. It was also the basis for Dreamforge's Dungeon Hack, published by SSI in 1993 for the PC. Dungeon Hack integrated Hack's gameplay into the popular Eye of the Beholder engine developed by Westwood Studios.
Noah Morgan's Larn (1986), offered a persistent starting level and a town with a bank, school, shop, and a tax office. Players must pay taxes if they play the game again after winning it (finding a potion to cure the character's daughter); the game's difficulty also increases.
Thomas Biskup's Ancient Domains of Mystery (ADOM) was released in 1994, and is probably the most complex of the lot. It offers quests, skills, and a selection of ten races and twenty characters classes. There are multiple ways to win the game, but the goal is always to stop Chaos from invading the land of Ancardia. There are, of course, many, many other roguelikes, which vary widely in theme and quality.
(click for full size) There are countless "roguelikes," or games that base most of their gameplay concepts on Rogue. Shown here, in various PC versions, are NetHack (top left), Angband (top right), Larn (bottom left), and Ancient Domains of Mystery (bottom right).
There have also been several attempts to recreate Rogue or one of its many derivatives with superior audiovisuals. Two examples of these are Jaakko Tapani Peltonen's NetHack: Falcon's Eye (2002) and Hansjoerg "Hajo" Malthaner's Iso-Angband (2003). Both of these depicted the dungeons in isometric perspective, and also boasted sound effects and music. Unfortunately, neither is in active development now, though Falcon's Eye lives as a fork called Vulture's Eye.
An ambitious and still ongoing project is Scourge, which offers a four-character party and quality audiovisuals. Although some gamers might think these games are huge leaps forward for Rogue, it's also possible to see them negatively.
The task of creating custom graphics for each object and creature in these games is a considerable undertaking that may very well distract developers from what most Rogue fans consider essential: the gameplay.
At least some fans of Rogue may also be resistant to advanced audiovisuals on principle. Malthaner, for instance, felt his project failed because of "acceptance. Not technical issues; these were solvable -- but acceptance was low.
Some people were almost openly hostile towards the idea of a graphical frontend." Purists continue to insist that the essence of Rogue is its gameplay; all efforts to "improve" the audiovisuals merely amount to a distraction, rather like trying to play chess with extremely elaborate pieces.
Falcon's Eye (top) and Iso-Angband (bottom) are two of many efforts to update roguelike gameplay with advanced graphics. The graphical frontends haven't seemed to catch on with many roguelike fans, however, who seem to prefer character-set graphics.
Although Rogue fans may clash over such issues, all agree that the game's main appeal is its gameplay. At its best, Rogue represents an addictive and compelling hack-and-slash type of experience. Unlike the majority of CRPGs, it's an easy game to pick up and play for a few minutes while waiting for a bus.
The character-set versions are also quite easy to get running on even the most limited hardware. The purists may have a good point; the lack of advanced audiovisuals does allow one to better appreciate the more abstract, mathematical nature of the genre. Indeed, perhaps the best way to think about Rogue is as the CRPG (or at least the "dungeon crawler") boiled down to its very essence.
This approach might explain its enduring appeal after so many advances in audiovisual technology, as well as why so many talented programmers continue to explore its potential.
[EDITOR'S NOTE: On sister alt.weblog GameSetWatch, John Harris' long-running @Play column presents perhaps the foremost extended analysis of the Rogue-like genre, in a series of longform articles.]
 This quotation is from Malthaner's private e-mail correspondence with the authors.