In the family of video game genres, Roguelikes are the crazy uncle that no one really talks about and most everyone agrees that is way past him prime. Everyone knows that without him the Diablo family wouldn't be around, but over the years he's refused to stay with the times and stodgily clings to his ASCII and tile-based graphics and midi-quality sound. In recent years he's started to let himself go, spawning a whole genre of Roguelike-likes and a mess of games with acronyms like 7DRLs and <1KBRLs. Though despite his lack of flashy graphics and sounds, he still manages to gather an audience.
Wikipedia explains that Roguelikes are "a sub-genre of role-playing video games, characterized by randomization for replayability, permanent death, and turn-based movement", which is probably a bit narrow for a definition, but not too bad, for Wikipedia at least. The Temple of the Roguelike provides a more in-depth take on what it means to be a Roguelike adding concepts like "Single command set", "Free form" and "Discovery mechcanics". Now you can probably count the number of games that claim to be Roguelikes and meet all of those criteria on one hand and have fingers left over. In fact, even the game that spawned the genre, Rogue itself, isn't what most people would consider free form. On top of that, none of these definitions mention the Roguelike-likes.
So, you ask, what do I consider the defining characteristics of a roguelike to be? Well, there is really only one trait I associate with Roguelikes and if any game exhibits this, I tend to think Roguelike, or at least Roguelikelike. The pace of play must fall between real time strategy and turn based strategy. To me, the rest are just conventions of the genre that can be ignored or changed, which separate Rougelikes from the Roguelike-likes. Games like Angband and Shiren the Wanderer: Mysterious Dungeon 2 that follow all the rules are considered roguelikes while games with only the pacing and a convention or two like Dwarf Fortress or Decker are considered roguelike-likes.
Today, the roguelike genre is still being developed by both amateurs and independent game designers, and while commercial releases are few and far between, companies like Bay 12 Games do reasonably well on donations. In addition, coming up next week is the yearly Seven Day Roguelike competition or 7DRL where developers attempt to code a roguelike from scratch in only 7 days. The 7DRL contest has grown over the years with more games being successfully completed each year.
Overall, Roguelikes are an interesting genre with a wide range of options to choose from when it comes time to choose a title to play. In a couple of weeks, there will be even more, and hopefully, if I can pull my act together, one of them will be my own 7DRL entry.