Rogue was one of the older rudimentary graphics (Usually using ascii characters for imagery) dungeon crawlers. The first of the *random created dungeon* games, that existed. This made sure you never played the same game twice. A very old dungeon crawler series that spawned a few others like NetHack, etc. The idea was you go down a dungeon that you had no idea what it looked like. There were monsters and all kinds of treasures to find, you also had just about every trapping of fantasy elements at your disposal. Enchanted weapons, unusual artifacts, magical spells and potions, etc. Some games allowed you to chose from a variety of character types to play as. The whole idea was that, even though the graphics were nothing much more than what you'd see for maps, these days, the level of detail and utilitarian uses for objects were unmatched. Sometimes, some freaky details of physics happened, in the game, that other games never thought of. For instance, making yourself levitate and then doing a big hit against a wall that (because you were floating) sends you flying back the other direction.
The games were fan and user supported, like Unix programs, and many many revisions ensued. Over time, these games had maybe thousands of unique objects to find, in which, it could be extremely rare that you'd see certain rare items in a hundred or so plays. (There's quite a few of those rares, now)
But the games had the one biggest risk among them. Sort of like the HARDCORE modes of certain games. (One of those games, being a very very late successor to the whole Rogue game-style. Diablo.) It is where if you die, your character was dead. No reviving, that's it. The moment you died, your character data was erased. If you want to keep playing, you need to make a new character and start over with a brand new dungeon. However, you are allowed to save your progress to continue later, as long as you aren't dead.
That's one of the reasons Hardcore was introduced, in the first place. To recreate that level of tension that it's age-old predecessor (in spirit) had. The fear of dying was at its highest, so that demanded more pre-thought on the player. Given the Rogue games were more turn-based (that is, nothing moved until the player moved), you could theoretically stop and plan what you do next.
All of those games, played today (or even within the last 14 years), are freely downloadable from a bunch of different sites and were recompiled for nearly every machine out there. The source code is also available.