Command-line snake game?

", is there such a free application in the official repositories (which is where I would prefer it to come from)?"

First there is nsnake that should meet your need exactly

sudo apt-get install nsnake

Two more I found are snake4 this opens in a new window though, so not a terminal game and gnibbles but I could not get it to run.

The game is called centipede and it full story can be found here: http://wp.subnetzero.org/?p=269. This is a bash game requiring no downloads and an interesting study for those interested in bash scripts.

You can change the size of the screen to make it smaller and more challenging by changing these variables:

LASTCOL=40                              # Last col of game area
LASTROW=20                              # Last row of game area

Here's the code:

#!/bin/bash
#
# Centipede game
#
# v2.0
#
# Author: [email protected]
#
# Functions

drawborder() {
   # Draw top
   tput setf 6
   tput cup $FIRSTROW $FIRSTCOL
   x=$FIRSTCOL
   while [ "$x" -le "$LASTCOL" ];
   do
      printf %b "$WALLCHAR"
      x=$(( $x + 1 ));
   done

   # Draw sides
   x=$FIRSTROW
   while [ "$x" -le "$LASTROW" ];
   do
      tput cup $x $FIRSTCOL; printf %b "$WALLCHAR"
      tput cup $x $LASTCOL; printf %b "$WALLCHAR"
      x=$(( $x + 1 ));
   done

   # Draw bottom
   tput cup $LASTROW $FIRSTCOL
   x=$FIRSTCOL
   while [ "$x" -le "$LASTCOL" ];
   do
      printf %b "$WALLCHAR"
      x=$(( $x + 1 ));
   done
   tput setf 9
}

apple() {
   # Pick coordinates within the game area
   APPLEX=$[( $RANDOM % ( $[ $AREAMAXX - $AREAMINX ] + 1 ) ) + $AREAMINX ]
   APPLEY=$[( $RANDOM % ( $[ $AREAMAXY - $AREAMINY ] + 1 ) ) + $AREAMINY ]
}

drawapple() {
   # Check we haven't picked an occupied space
   LASTEL=$(( ${#LASTPOSX[@]} - 1 ))
   x=0
   apple
   while [ "$x" -le "$LASTEL" ];
   do
      if [ "$APPLEX" = "${LASTPOSX[$x]}" ] && [ "$APPLEY" = "${LASTPOSY[$x]}" ];
      then
         # Invalid coords... in use
         x=0
         apple
      else
         x=$(( $x + 1 ))
      fi
   done
   tput setf 4
   tput cup $APPLEY $APPLEX
   printf %b "$APPLECHAR"
   tput setf 9
}

growsnake() {
   # Pad out the arrays with oldest position 3 times to make snake bigger
   LASTPOSX=( ${LASTPOSX[0]} ${LASTPOSX[0]} ${LASTPOSX[0]} ${LASTPOSX[@]} )
   LASTPOSY=( ${LASTPOSY[0]} ${LASTPOSY[0]} ${LASTPOSY[0]} ${LASTPOSY[@]} )
   RET=1
   while [ "$RET" -eq "1" ];
   do
      apple
      RET=$?
   done
   drawapple
}

move() {
   case "$DIRECTION" in
      u) POSY=$(( $POSY - 1 ));;
      d) POSY=$(( $POSY + 1 ));;
      l) POSX=$(( $POSX - 1 ));;
      r) POSX=$(( $POSX + 1 ));;
   esac

   # Collision detection
   ( sleep $DELAY && kill -ALRM $$ ) &
   if [ "$POSX" -le "$FIRSTCOL" ] || [ "$POSX" -ge "$LASTCOL" ] ; then
      tput cup $(( $LASTROW + 1 )) 0
      stty echo
      echo " GAME OVER! You hit a wall!"
      gameover
   elif [ "$POSY" -le "$FIRSTROW" ] || [ "$POSY" -ge "$LASTROW" ] ; then
      tput cup $(( $LASTROW + 1 )) 0
      stty echo
      echo " GAME OVER! You hit a wall!"
      gameover
   fi

   # Get Last Element of Array ref
   LASTEL=$(( ${#LASTPOSX[@]} - 1 ))
   #tput cup $ROWS 0
   #printf "LASTEL: $LASTEL"

   x=1 # set starting element to 1 as pos 0 should be undrawn further down (end of tail)
   while [ "$x" -le "$LASTEL" ];
   do
      if [ "$POSX" = "${LASTPOSX[$x]}" ] && [ "$POSY" = "${LASTPOSY[$x]}" ];
      then
         tput cup $(( $LASTROW + 1 )) 0
         echo " GAME OVER! YOU ATE YOURSELF!"
         gameover
      fi
      x=$(( $x + 1 ))
   done

   # clear the oldest position on screen
   tput cup ${LASTPOSY[0]} ${LASTPOSX[0]}
   printf " "

   # truncate position history by 1 (get rid of oldest)
   LASTPOSX=( `echo "${LASTPOSX[@]}" | cut -d " " -f 2-` $POSX )
   LASTPOSY=( `echo "${LASTPOSY[@]}" | cut -d " " -f 2-` $POSY )
   tput cup 1 10
   #echo "LASTPOSX array ${LASTPOSX[@]} LASTPOSY array ${LASTPOSY[@]}"
   tput cup 2 10
   echo "SIZE=${#LASTPOSX[@]}"

   # update position history (add last to highest val)
   LASTPOSX[$LASTEL]=$POSX
   LASTPOSY[$LASTEL]=$POSY

   # plot new position
   tput setf 2
   tput cup $POSY $POSX
   printf %b "$SNAKECHAR"
   tput setf 9

   # Check if we hit an apple
   if [ "$POSX" -eq "$APPLEX" ] && [ "$POSY" -eq "$APPLEY" ]; then
      growsnake
      updatescore 10
   fi
}

updatescore() {
   SCORE=$(( $SCORE + $1 ))
   tput cup 2 30
   printf "SCORE: $SCORE"
}
randomchar() {
    [ $# -eq 0 ] && return 1
    n=$(( ($RANDOM % $#) + 1 ))
    eval DIRECTION=\${$n}
}

gameover() {
   tput cvvis
   stty echo
   sleep $DELAY
   trap exit ALRM
   tput cup $ROWS 0
   exit
}

###########################END OF FUNCS##########################

# Prettier characters but not supported
# by all termtypes/locales
#SNAKECHAR="\0256"                      # Character to use for snake
#WALLCHAR="\0244"                       # Character to use for wall
#APPLECHAR="\0362"                      # Character to use for apples
#
# Normal boring ASCII Chars
SNAKECHAR="@"                           # Character to use for snake
WALLCHAR="X"                            # Character to use for wall
APPLECHAR="o"                           # Character to use for apples
#
SNAKESIZE=3                             # Initial Size of array aka snake
DELAY=0.2                               # Timer delay for move function
FIRSTROW=3                              # First row of game area
FIRSTCOL=1                              # First col of game area
LASTCOL=40                              # Last col of game area
LASTROW=20                              # Last row of game area
AREAMAXX=$(( $LASTCOL - 1 ))            # Furthest right play area X
AREAMINX=$(( $FIRSTCOL + 1 ))           # Furthest left play area X
AREAMAXY=$(( $LASTROW - 1 ))            # Lowest play area Y
AREAMINY=$(( $FIRSTROW + 1))            # Highest play area Y
ROWS=`tput lines`                       # Rows in terminal
ORIGINX=$(( $LASTCOL / 2 ))             # Start point X - use bc as it will round
ORIGINY=$(( $LASTROW / 2 ))             # Start point Y - use bc as it will round
POSX=$ORIGINX                           # Set POSX to start pos
POSY=$ORIGINY                           # Set POSY to start pos

# Pad out arrays
ZEROES=`echo |awk '{printf("%0"'"$SNAKESIZE"'"d\n",$1)}' | sed 's/0/0 /g'`
LASTPOSX=( $ZEROES )                    # Pad with zeroes to start with
LASTPOSY=( $ZEROES )                    # Pad with zeroes to start with

SCORE=0                                 # Starting score

clear
echo "
Keys:

 W - UP
 S - DOWN
 A - LEFT
 D - RIGHT
 X - QUIT

If characters do not display properly, consider changing
SNAKECHAR, APPLECHAR and WALLCHAR variables in script.
Characters supported depend upon your terminal setup.

Press Return to continue
"

stty -echo
tput civis
read RTN
tput setb 0
tput bold
clear
drawborder
updatescore 0

# Draw the first apple on the screen
# (has collision detection to ensure we don't draw
# over snake)
drawapple
sleep 1
trap move ALRM

# Pick a random direction to start moving in
DIRECTIONS=( u d l r )
randomchar "${DIRECTIONS[@]}"

sleep 1
move
while :
do
   read -s -n 1 key
   case "$key" in
   w)   DIRECTION="u";;
   s)   DIRECTION="d";;
   a)   DIRECTION="l";;
   d)   DIRECTION="r";;
   x)   tput cup $COLS 0
        echo "Quitting..."
        tput cvvis
        stty echo
        tput reset
        printf "Bye Bye!\n"
        trap exit ALRM
        sleep $DELAY
        exit 0
        ;;
   esac
done