is a display oriented dungeons & dragons-like game. Both display and command structure resemble rogue. (For a game with the same structure but entirely different display - a real cave instead of dull rectangles - try Quest.)
To get started you really only need to know two commands. The command ? will give you a list of the available commands and the command / will identify the things you see on the screen.
To win the game (as opposed to merely playing to beat other people's high scores) you must locate the Amulet of Yendor which is somewhere below the 20th level of the dungeon and get it out. Nobody has achieved this yet and if somebody does, he will probably go down in history as a hero among heroes.
When the game ends, either by your death, when you quit, or if you escape from the caves, will give you (a fragment of) the list of top scorers. The scoring is based on many aspects of your behavior but a rough estimate is obtained by taking the amount of gold you've found in the cave plus four times your (real) experience. Precious stones may be worth a lot of gold when brought to the exit. There is a 10% penalty for getting yourself killed.
The administration of the game is kept in the directory specified with the -d option, or, if no such option is given, in the directory specified by the environment variable HACKDIR or, if no such variable exists, in the current directory. This same directory contains several auxiliary files such as lockfiles and the list of topscorers and a subdirectory save where games are saved. The game administrator may however choose to install hack with a fixed playing ground, usually /var/games/bsdgames/hack
The -n option suppresses printing of the news.
The -u playername option supplies the answer to the question "Who are you?". When playername has as suffix one of -T -S -K -F -C or -W then this supplies the answer to the question "What kind of character ... ?".
The -s option will print out the list of your scores. It may be followed by arguments -X where X is one of the letters C, F, K, S, T, W to print the scores of Cavemen, Fighters, Knights, Speleologists, Tourists or Wizards. It may also be followed by one or more player names to print the scores of the players mentioned.