Sample code showing off how PixelVision8 (http://pixelvision8.com) works to display and animate a sprite and capture player imput.

code.lua

local apiBridge = LuaBridge()

-- Gameboy Game
-- Resolution 160 x 144
-- Max sprites: 40

-- variables for game
animDelay = 0
animTime = .5
currentAnim = 0
totalFrames = 2
dir = 0
flipH = false
x = 50
y = 50

function init()
	-- change the bg color
	apiBridge:ChangeBackgroundColor(2)
end

function update()
	
	-- capture imput
	if(apiBridge:ButtonDown(0, 0)) then
		-- show back of player
		dir = 1
		flipH = false
	elseif (apiBridge:ButtonDown(1, 0)) then
		-- show front of player
		dir = 0
		flipH = false
	elseif(apiBridge:ButtonDown(2, 0)) then
		-- show side of player and toggle flip
		dir = 2
		flipH = true
	elseif (apiBridge:ButtonDown(3, 0)) then
		-- show side of player and toggle flip
		dir = 2
		flipH = false
	end

	-- update animation timer
	animDelay = animDelay + apiBridge.delta
	
	-- see if we should change animation
	if(animDelay > animTime) then 
		
		-- reset the delay
		animDelay = 0

		-- update the current frame
		currentAnim = currentAnim + 1

		-- make sure we reset the frame counter when out of frames
		if(currentAnim >= totalFrames) then
			currentAnim = 0
		end
	end

end

function draw()
	
	-- clear the display
	apiBridge:Clear()
	
	-- calcualte the correct sprite for the player 
	spriteID = currentAnim + (dir * totalFrames)

	-- draw sprite to display
	apiBridge:DrawSprite(spriteID , x, y, flipH, false, true)
end