Some quotes about the history of Nethack and what gameplay is like:
NetHack evolved from Hack, which added character classes, pets and shops to the basic features of the original Rogue game. The first version of NetHack (1.3d) was released on 28 July 1987, and the current version (3.4.3) on 9 December 2003.
Hack was originally written by Jay Fenlason, then heavily modified by Andries Brouwer. Hack was ported to several different operating systems in 1986, then all the versions were merged into a single port by Mike Stephenson called NetHack. NetHack deviated significantly from any one version of Hack that it is considered a new game.
This quote is primarily about the precursor game 'Hack', but it pertains just as much to Nethack as it does to Hack:
Hack is the precursor to NetHack, both members of the family of text-based Rogue-like games. The gameplay of Rogue and its descendants is the quintessential role-playing game (RPG): Choose a character class and venture forth into the dungeon to fight monsters and gain treasure.
Like all descendants of Rogue, Hack is displayed from a top-down view, painted with text characters. The player ventures throughout the dungeon, visiting rooms connected by thin corridors. Gameplay is turn-based, with the turn beginning with the player's action (move, attack, eat, cast spell, etc.). Commands are mapped to various letters of the keyboard, including "i" for inventory, "e" for eat food, etc. with one exception: Attacking a monster involves running into it, so the "attack" function shares the same keys as movement.
Hack is one of the first significant deviations from Rogue, notable by the rich interaction possible in the game world: Simple actions result in complex (yet logical) reactions. For example, it is not uncommon to throw a boomerang only to miss the target and have it return to hit the player; or kill a monster that has the ability to turn you to stone as an attack, then accidentally step on its carcass on the way out and turn to stone; or having a bolt of fire from a magic wand ricochet around the room, hit the player, and cause his magic scrolls to catch on fire; etc. In addition, monsters and objects have secondary, hidden properties; for example, killing and eating a leprechan will result in the player randomly teleporting to different locations.
The files provided here also includes several spoilers for the game - even with the spoilers available, this game is very difficult, and can provide hours upon hours of gameplay, with no two games ever being alike (random dungeon generation).
Since the advent of Windows Vista and 7, you can no longer run DOS apps in fullscreen mode. Makes playing Nethack kind of a strain on the eyes, especially if you have a very high res monitor.
So, I decided to revisit compiling Nethack under DOS in the hope of adding a couple other features I wanted as well as some bug fixes. Took awhile... had to re-learn how to compile Nethack under DOS and learned a few things in the process compared to my first attempt at it from two years ago. Result - a much cleaner build with no errors during the compile and subsequent patch process. Here's a list of the changes made: