NidhOX

Nidhogg Open-source eXperience: a two-player fencing game played in a terminal on Cauldron, from your own copy of the game's files.

No game files are included. NidhOX reads the data file of a copy you own — data.win from the Windows build, or game.ios from inside the macOS build's Nidhogg.app — and draws its rooms from it. With data.win it also reads the Nidhogg.exe installed beside it, for the depths the game creates its objects at; a data.win without it does not start.

mix deps.get
mix nidhox
mix nidhox --area Wilds
mix nidhox --data path/to/data.win

--data defaults to NIDHOX_DATA, then the first of the usual Steam installs under your home directory: CrossOver's, macOS's and Linux's (set in config/runtime.exs). --area is the area the level select starts on: Cemetery (the default), Castle, Mines, Sky or Wilds.

Controls

Two players share the keyboard, or play with a controller each:

Either side's keys work the menus; jump or Esc goes back. Ctrl+Q quits at once.

Controllers take the free sides in the order they connect; Options → Controls → Controllers lists the connected ones and moves each between player 1, player 2 and none, and the choice is kept for that controller.

Modes

NidhOX opens on the logos, then the title. Press Enter (or attack) to reach the menu. The menus turn like a wheel under the logo, the selected line in the middle; up and down turn them, Enter or attack chooses, and jump goes back (on the main menu, to Quit to desktop). Left on the title for twenty seconds, the computer plays a match against itself; any key brings back the menu.

• Multiplayer

  • Offline versus: two players at one keyboard, or a controller each. The level select pans across the map; up and down pick the area, Enter or attack starts the bout. Left alone for twelve seconds, it goes back to the main menu. After a bout the match statistics show; up or down switches their bottom line between going on and watch replay, which plays the bout again (Enter skips it).

  • Online versus: one machine hosts and another joins it; both play in the host's game.

    • Host shows this machine's address and a join code. Tell both to the player joining. Hosting stops when you go back (jump or Esc).

    • Host over SSH serves the game over ssh instead. It first asks for the port: leave it empty for any free one, or type one (NIDHOX_SSH_PORT or mix nidhox --ssh-port fills it in). It then shows the command to give the other player: ssh -p <port> new@<address>. They need only an ssh client — no copy of the game. The first time, any password opens a form where they pick a name and password, and they connect as that name from then on. They play orange in this machine's game, in their own terminal; sound reaches them only through an ssh -R tunnel to a player program on their machine. They have 10 minutes from connecting to log in. The game reaches them at 20 frames a second, fewer on a connection too slow for that. Going back, quitting to the title or quitting the game stops serving; they are disconnected with their terminal put back as it was and a line saying the host stopped.

      On a terminal that keeps images, how the picture is sent can be chosen when starting the game, for every player including those over ssh, with mix nidhox --picture (or NIDHOX_PICTURE) and any of, comma separated: native draws the room at its own size times the largest whole number that fits the window, or native:2, native:3, … at that many times; size:WxH sets the size itself; png sends each frame as a PNG, smaller; swap replaces each frame without the picture going blank in between. The default is native:2,png,swap; --picture none sends the picture at the window's cells as raw pixels instead.

    • Join lists the hosts on your local network; pick one and type its code.

    • Set IP types a host's address (it starts with your own network's part), then its code.

    Typing: type the address or code on the keyboard (letters come out in capitals); Backspace and Delete erase, the arrows move the caret, Enter finishes and Esc goes back. With a controller, up and down change the character before the caret. If the typing box closes, press start or attack to bring it back. The joining player plays orange.

    If the other player leaves, the bout under way is yours by forfeit and the hosting screen comes back saying "the other player left", still hosting on the same port (or address and code), so another player can connect straight away. When the other player chooses QUIT TO TITLE SCREEN from the pause, they leave: their ssh session or game ends and this machine goes back to the hosting screen the same way, saying "the other player quit". A second copy of the game on the same machine can join the first; it plays as your name with " (2)" after it.

    The code admits the joining machine fully to the host's Erlang VM, so give it only to the player you are playing with. On a local network this needs nothing more. Across the internet, the host starts with a fixed port (mix nidhox --port 9200) and opens it and port 4369 to the joining machine; the traffic is not encrypted.

  • Variants: the game's own. Time limit (none, or 3:00 to 9:30 in half minutes; when it runs out, the bout goes on in the area's sudden death room, where the first kill wins), then divekicks, throws, no swords, throws only, baby mode, low gravity, sudden death only, skippy mode, turbo, slow, spine swords, boomerang swords and trails, each on or off, as many at once as you like. Attack or start changes the one selected.

• Tournament — 3 to 8 players taking turns at the two sides, single elimination. Set Players and the Map with left and right, and the Variants, then Start tournament. The ladder shows the bracket, the next two players flashing; a player drawn against an empty place (X) goes through. Enter or attack leads to a nine-second warm-up in which the next two find their controllers and can already fence, then their match; the first of the two plays yellow. The last player left is the champion; their room ends the tournament after ten seconds or on Enter.
• Options — Controls to remap each player's keys, flashing and persistent blood on or off, and music and sound effect sliders (left and right; the effects level scales the music too, as in the game). They are kept in your settings, ~/.config/nidhox/<name>.settings. They are on the pause menu as well.
• Credits — from your copy's credits.txt.
• Quit to desktop
• How to play — the game's own lessons, one at a time, with an orange dummy.
• Single player — sixteen bouts against the computer across the Mines, Sky, Wilds and Castle, each against a different opponent and harder as you go. The map shows your run and its time; press attack or start to fight the next bout. Lose and you fight that opponent again; win the last and the game is complete, with your time.
• Challenge — you against a computer opponent that gets harder each time you kill it. Every move that lands scores its worth: lunge, snap, kick, punch, sweep, guard, parry, throw and dodge. A move's worth halves each time you use it and climbs back while you use others, so vary them. Dying ends the run; your best score is shown along the bottom. Enter or Esc pauses.

Enter or Esc during a bout pauses it: unpause, change level (versus), quit to the title, or options. After a bout come its time, the winner, and each side's kills and suicides; any press goes on to the level select. Every bout's result is kept, per player, in ~/.local/share/nidhox/ledger.dets.

How it plays

Two fencers start in the middle of an area. Yellow wants to reach the far right end, orange the far left.

• Stance. Up and down move your sword between high, middle and low. A thrust is parried by an opponent who faces you with the sword at the same height; it kills one holding it anywhere else.
• Disarm. Moving your sword into the height of a thrust just before it lands knocks the attacker's sword away.
• Throw. Hold up in high stance and attack to throw your sword. It kills whoever it reaches, unless they face it with their sword held high.
• Unarmed. Without a sword, attack is a punch that knocks the opponent's sword away. Duck over a sword on the ground to pick it up.
• Right of way. Killing your opponent lets you run on towards your goal; the camera follows you, and your opponent comes back ahead of you. Only you can leave the screen, into the next room. Falling into a pit hands the right of way to your opponent.
• Winning. Reach the goal at your end of the area. The next bout starts in the middle.

The rooms, their scenery and ground, the fencers, the menus and their lettering, the sounds and the music all come from your copy of the game.