Game of Life in Codea | Video available here http://www.youtube.com/watch?v=G5yg64joL-8

Board.lua

Board = class()

CELL_SIZE = 30

function Board:init(size)
    self.grid = {}
    for i = 1, size do
        self.grid[i] = {}
        for j = 1, size do
            self.grid[i][j] = false
        end 
    end        
end

function Board:draw()
    -- Codea does not automatically call this method

    stroke(176, 176, 176, 255)
    strokeWidth(1)
    
    for i = 1, #self.grid do
        for j = 1, #self.grid[i] do
            if (self.grid[i][j]) then
                fill(0, 0, 0, 255)
            else
                fill(255, 255, 255, 255)
            end
            rect(i * CELL_SIZE, j * CELL_SIZE, CELL_SIZE, CELL_SIZE)
        end 
    end
end

function Board:setCellAt(x, y, isAlive)
    self.grid[x][y] = isAlive
end

function Board:copyGrid()
    self.copy = self.grid
    self.grid = {}
    for i = 1, #self.copy do
        self.grid[i] = {}
        for j = 1, #self.copy[i] do
            self.grid[i][j] = self.copy[i][j]
        end 
    end
 end

function Board:countNeighboursAt(x, y)
    -- deal with edges
    minX = math.max(x - 1, 1)
    maxX = math.min(x + 1, #self.copy)
    minY = math.max(y - 1, 1)
    maxY = math.min(y + 1, #self.copy[1])
    
    -- count live cells in the radius that are not this one
    count = 0
    for i = minX, maxX do
        for j = minY, maxY do
            if not (x == i and y == j) and self.copy[i][j] then
                count = count + 1
            end
        end
    end
    return count    
end

function Board:shouldBeAliveAt(x, y)
    neighbours = self:countNeighboursAt(x, y)
    return (self.copy[x][y] and (neighbours == 2 or neighbours == 3)) or
        (not self.copy[x][y] and neighbours == 3)
end
        
function Board:evolve()
    self:copyGrid()
       
    for i = 1, #self.grid do
        for j = 1, #self.grid[i] do
            self.grid[i][j] = self:shouldBeAliveAt(i, j)
        end 
    end
    
    
end

function Board:touched(touch)
    -- Codea does not automatically call this method
    if touch.state ~= ENDED then
        x = math.floor(touch.x/CELL_SIZE)
        y = math.floor(touch.y/CELL_SIZE)
        if x >= 1 and x <= #self.grid and y >= 1 and y <= #self.grid[x] then
            self:setCellAt(x, y, true)
        end
    end
end

Main.lua

BOARD_SIZE = 24

-- Use this function to perform your initial setup
function setup()
    frame=0
    board = Board(BOARD_SIZE)
    
    -- cool initial state
    board:setCellAt(2,1,true)
    board:setCellAt(3,2,true)
    board:setCellAt(1,3,true)
    board:setCellAt(2,3,true)
    board:setCellAt(3,3,true)
    board:setCellAt(17,8,true)
    board:setCellAt(18,8,true)
    board:setCellAt(19,8,true)
end

-- This function gets called once every frame
function draw()
    background(255, 255, 255, 255)

    board:draw()
    
    -- manually reduce frame rate...
    if frame % 5 == 0 then
        board:evolve()
    end
    
    frame = frame + 1
end

function touched(touch)
    board:touched(touch)
end

Video of the result is available here: http://www.youtube.com/watch?v=G5yg64joL-8