Game Development with LÖVE

LÖVE (love2d.org) is a free framework for 2D games in Lua. It handles graphics, sound, input, and physics; you write the game logic in callbacks.

The game loop

-- illustrative
-- main.lua — run with: love .
local player = {x = 400, y = 300, speed = 200, size = 20}
local coins = {}
local score = 0

function love.load()
  love.window.setTitle("Coin Collector")
  math.randomseed(os.time())
  for _ = 1, 5 do
    table.insert(coins, {x = math.random(20, 780), y = math.random(20, 580)})
  end
end

function love.update(dt)                  -- dt: seconds since last frame
  if love.keyboard.isDown("left")  then player.x = player.x - player.speed * dt end
  if love.keyboard.isDown("right") then player.x = player.x + player.speed * dt end
  if love.keyboard.isDown("up")    then player.y = player.y - player.speed * dt end
  if love.keyboard.isDown("down")  then player.y = player.y + player.speed * dt end

  for i = #coins, 1, -1 do
    local c = coins[i]
    if math.abs(c.x - player.x) < player.size and math.abs(c.y - player.y) < player.size then
      table.remove(coins, i)
      score = score + 1
    end
  end
end

function love.draw()
  love.graphics.setColor(1, 0.8, 0)
  for _, c in ipairs(coins) do love.graphics.circle("fill", c.x, c.y, 8) end
  love.graphics.setColor(0.3, 0.7, 1)
  love.graphics.rectangle("fill", player.x - 10, player.y - 10, 20, 20)
  love.graphics.setColor(1, 1, 1)
  love.graphics.print("Score: " .. score, 10, 10)
end

• love.load runs once at the start; love.update(dt) and love.draw run every frame (usually 60 times per second).
• Multiplying speeds by dt makes movement independent of frame rate.
• Other callbacks handle input events: love.keypressed(key), love.mousepressed(x, y, button).

Structuring a larger game

• Game states — menu, playing, paused, game over — each a module with its own update/draw (the hump.gamestate library helps).
• Entities as classes (see the OOP lessons) with update(dt) and draw() methods, kept in a list.
• Libraries — bump.lua (collision), anim8 (sprite animation), hump.timer (tweens and delays), and love.physics (Box2D).
• Distribution — zip the folder as a .love file, or fuse it with the LÖVE executable for Windows, macOS, Linux, Android, and iOS.

Other Lua game engines include Defold (a full editor, used for commercial mobile games), Solar2D, and PICO-8 (a "fantasy console" using a Lua subset).