Play the game of Go in your Vim! Use the cursor to move around on the board, press <enter> to place a stone. Ask the computer to :Undo your move or :Cheat and play for you. Save and load games by writing or editing a filename.

Requirements

This plugin requires Vim with +job. Vim 8 will do, but you can even use a Vim 7.4 with a late enough patch level. Check the output of :version. It should also work on Neovim, but it hasn't been tested with recent versions.

You'll also need GnuGo installed, since Vim simply interacts with that program. For example, on Arch Linux, you can install it with:

# pacman -S gnugo

For other platforms, check the GnuGo project's homepage: https://www.gnu.org/software/gnugo/download.html.

Usage

To start a new GnuGo game, just run the :Gnugo command. This will open a new buffer with an empty board:

= Last command:
= Last location:
= Game Mode:     black
=
   A B C D E F G H J K L M N O P Q R S T
19 . . . . . . . . . . . . . . . . . . . 19
18 . . . . . . . . . . . . . . . . . . . 18
17 . . . . . . . . . . . . . . . . . . . 17
16 . . . + . . . . . + . . . . . + . . . 16
15 . . . . . . . . . . . . . . . . . . . 15
14 . . . . . . . . . . . . . . . . . . . 14
13 . . . . . . . . . . . . . . . . . . . 13
12 . . . . . . . . . . . . . . . . . . . 12
11 . . . . . . . . . . . . . . . . . . . 11     WHITE (O) has captured 0 stones
10 . . . + . . . . . + . . . . . + . . . 10     BLACK (X) has captured 0 stones
 9 . . . . . . . . . . . . . . . . . . . 9
 8 . . . . . . . . . . . . . . . . . . . 8
 7 . . . . . . . . . . . . . . . . . . . 7
 6 . . . . . . . . . . . . . . . . . . . 6
 5 . . . . . . . . . . . . . . . . . . . 5
 4 . . . + . . . . . + . . . . . + . . . 4
 3 . . . . . . . . . . . . . . . . . . . 3
 2 . . . . . . . . . . . . . . . . . . . 2
 1 . . . . . . . . . . . . . . . . . . . 1
   A B C D E F G H J K L M N O P Q R S T

You play as black by default. To place a stone, position the cursor on an empty space (a "." or "+" character) and press the <enter> key. You can also use the "x" and "o" keys for the same purpose, but note that these keys have different meanings in "manual" mode. Either way, while playing as black or white, the computer will automatically play the next move with the other color.

You can also place a stone by providing its coordinates to the :Play command:

:Play D4

If you're unsure what to do next, you can cheat and have the computer play a move for you with the :Cheat command:

:Cheat

If you'd like to undo the last move, you can use the :Undo command:

:Undo

While you're playing as black or white, the command will undo two moves -- the last computer move, and your last move. If you're in "manual" mode, it will only undo one move. If you'd like, you can map this command to the "u" key for this buffer, by creating the file ~/.vim/ftplugin/gnugo.vim and mapping it only for this buffer:

nnoremap <buffer> u :Undo<cr>

But be careful -- this means that, if you accidentally delete something in the buffer, you can't undo it -- the "u" key now means something else.

You can redraw the board with the :Redraw command:

:Redraw

Changing colors

If you'd like to play as white, you can start the game with:

:Gnugo white

If you'd like to change sides halfway through, you can use the :ChangeMode command. Note that, if you're currently playing as black, you probably want to :Cheat once, since the last move was probably the computer's, and the computer should now play with your former color.

:ChangeMode white
:Cheat

The same thing goes if you're playing with the white pieces and would like to switch to playing with the black ones.

Manual mode

You can run the game in "manual" mode, which means the computer doesn't automatically play against you, and you don't automatically play with a particular color.

In this mode, you can't use :Play or :Cheat, you need to use the :Execute command, which lets you send commands directly to GnuGo's gtp server:

" play as black, on D4
:Execute play black D4

" have the computer generate a move for white
:Execute genmove white

You can now play several times with black/white, if you're so inclined, and you can play with another person on the same machine. For convenience's sake, you can use the o key to play a white move, and the x key to play a black move (in the ASCII representation of the board, black pieces are marked with "X" and white pieces are marked as "O").

Additional arguments

When starting the game, you can provide additional arguments that are fed directly to the gnugo command. Check gnugo --help for details. As an example, you can start the game with a different board size like so:

:Gnugo black --boardsize=13

Loading and saving

If you'd like to save your game, you can just :write the gnugo buffer to a .sgf file:

:Gnugo black
:Play D4
:w strong_start.sgf

Later, you can load your game by simply editing that same .sgf file, either from Vim, with :edit, or from the command-line:

$ vim strong_start.sgf

You'll be asked whether you want to resume your last game. The prompt is there to allow you to directly edit the sgf file, if you need to, for whatever reason (like if you're writing this particular Vim plugin and need to see the contents of the file).

You can also edit a non-existing sgf file, and Vim will ask you if you'd like to start a new Go game with that name. Note that the file extension needs to be .sgf. If you'd like to open a savegame file with a different extension, use the :GnugoLoad command:

GnugoLoad saved_file.txt

This will read the file and start the game in the current buffer, so be sure to open one with :new if you're currently editing something else.

Internals

The plugin uses Vim's job functions to spawn a gnugo --mode gtp process. The process is connected to the buffer, and when the buffer is closed, an autocommand sends the "quit" command to it. On my machine, this seems to keep the process around as a zombie for a few seconds, but it then gets reaped by the system. I figure it's not a big deal, so I've left it like this. If you understand processes better than me and know something different that should be done in this situation, please open an issue with your suggestion.