Unlike many other Dungeons & Dragons-inspired games, the emphasis in NetHack is on discovering the detail of the dungeon and not simply killing everything in sight - in fact, killing everything in sight is a good way to die quickly. Each game presents a different landscape - the random number generator provides an essentially unlimited number of variations of the dungeon and its denizens to be discovered by the player in one of a number of characters: you can pick your race, your role, and your gender.
Save Game Changes: Nethack changed the way it saved games. If you created a save game with a version prior to 3.6.6, you will need to open your NetHackPortable\Data\saves directory and rename your saved game to remove your Windows username from the beginning. So rename WindowsUser-Character.NetHack-saved-game to Character.NetHack-saved-game.
Invalid Settings Close: If you attempt to create a character with an invalid combination of attributes, Nethack will close with no error when you click OK.
