A member of the battleship family of abstract games. Like battleship, it also is played with some paper and pencils between two people, each trying to guess the other's board layout.

Octo is played on an 8x8 grid. Each player places onto this grid 8 contiguous groups of 8 cells each. An example board is below.


  ABCDEFGH
 +--------+
1|ggggfffh|1
2|dddggefh|2
3|dadgeefh|3
4|aadgeffh|4
5|addeefch|5
6|aaabeech|6
7|babbbcch|7
8|bbbcccch|8
 +--------+
  ABCDEFGH
Once both players have set up boards, they then call off rectangles battleship style. The opponent then replies with the number of each letter in that area.
C1,E3 -> "2 from section d, 1 from section e, 1 from section f,5 from section g"
F7,G8 -> "4 from section c"

The game continues until one person thinks they have the other person's layout. The guess is compared to the actual. If the guess matches, the guesser is the winner. If the guess fails, the guesser is the looser.