The evolution continues with a 3 foot tall Indonesian fellow.

players/homo_floresiensis.rb

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+require "rubygems"
+require "ruby-debug"
+
+class HomoFloresiensis
+  attr_accessor :last_move, :board, :moves_to_make
+
+  def initialize
+    @board = Board.new
+  end
+
+  def name
+    "Homo Floresiensis"
+  end
+
+  def new_game
+    [2, 3, 3, 4, 5].inject([]) { |placed, length| placed.push(Placement.create_for_length_and_context(length, placed)) }
+  end
+
+  def take_turn(state, ships_remaining)
+    board.push_state(state)
+    board.next_move
+  end
+
+  class Placement
+    attr_reader :length, :context, :direction
+
+    def self.create_for_length_and_context(length, context)
+      new(length, context).value
+    end
+
+    def initialize(length, context)
+      @length = length
+      @context = context
+    end
+
+    def direction
+      @direction ||= [:across, :down].sample
+    end
+
+    def value
+      @value ||= (generate_coords + [length, direction])
+    end
+
+    private
+
+    def generate_coords
+      try = [rand(10-length), rand(10)]
+      try.reverse! if direction == :down
+
+      is_succcessful_attempt(try) ? try : generate_coords
+    end
+
+    def is_succcessful_attempt(try)
+      context.all? { |placement|
+        (expand(*try) & self.class.expand(*placement)).empty?
+      }
+    end
+
+    def expand(x, y)
+      self.class.expand(x, y, length, direction)
+    end
+
+    def self.expand(x, y, length, direction)
+      xy         = "#{x}#{y}".to_i
+      multiplier = direction == :down ? 1 : 10
+      coords     = (0...length).map{ |i| xy + i * multiplier }
+    end
+
+  end
+
+  class Board
+    attr_reader :states, :moves_made, :avaliable_moves
+
+    def initialize
+      @states = []
+      @moves_made = []
+      @avaliable_moves = []
+    end
+
+    def state
+      states.last
+    end
+
+    def last_move
+      moves_made.last
+    end
+
+    def push_state(state)
+      @states << state
+      @avaliable_moves += valid_moves_around_last_move if last_move_was_hit?
+    end
+
+    def next_move
+      move = get_move
+      moves_made << move
+
+      move
+    end
+
+    private
+
+    def get_move
+      move = if avaliable_moves.empty?
+               [rand(10), rand(10)]
+             else
+               avaliable_moves.pop
+             end
+
+      is_succcessful_attempt(move) ? move : get_move
+    end
+
+    def is_succcessful_attempt(try)
+      state[try[1]][try[0]] == :unknown
+    end
+
+    def valid_moves_around_last_move
+      moves = []
+
+      moves << [last_move[0], last_move[1]+1] if last_move[1]+1 < 10
+      moves << [last_move[0], last_move[1]-1] if last_move[1]-1 >= 0
+
+      moves << [last_move[0]+1, last_move[1]] if last_move[0]+1 < 10
+      moves << [last_move[0]-1, last_move[1]] if last_move[0]-1 >= 0
+
+      moves
+    end
+
+    def last_move_was_hit?
+      !moves_made.empty? && state[last_move[1]][last_move[0]] == :hit
+    end
+  end
+end
+