Wallvoid, a simple game made in Codea where the user must tap before the UFO exits the screen, the UFO then heading in a semi-opposite direction. http://twolivesleft.com/Codea/

Wallvoid.lua

--This game only works in the Codea app for iPad (which uses Lua); http://twolivesleft.com/Codea/
--This code was originally made in April 2014.
function setup()
    score = 0
    hit = 0
    x=380 --starting x
    y=400 --starting y
    d=100 --diameter of ball
    dx = 0
    dy = 0
    k = 0
    alrighty = 0
end

function draw()
    background(0, 0, 0, 255)
    pushStyle()
    sprite("Space Art:UFO",x,y,d)
    font("HelveticaNeue-Bold")
    textAlign(CENTER)
    fill(255, 255, 255, 255)
    --lel = string.format("%.f",(ElapsedTime - alrighty))
    if score == 0 then
        alrighty = ElapsedTime
    elseif score == 1 then
        alrighty = ElapsedTime
    end
    text("Score: " .. score .. "\n\nTap screen when UFO is about to hit wall.\n\nYou have survived for " .. string.format("%.f",(ElapsedTime - alrighty)) .. " seconds.", 380, 555)
    fontSize(50)
    popStyle()
    --[[ change direction if we hit a wall
    if x>WIDTH-d/2 or x<d/2 then dx=-dx  score = score + 1 print("You hit a wall! Try again") end
    if y>HEIGHT-d/2 or y<d/2 then dy=-dy end
    ]]
    if x>WIDTH-d/2 or x<d/2 or y>HEIGHT-d/2 or y<d/2 then y = 400 x = 380 oldscore = score print("You just got a score of " .. oldscore ..  "!") score = 0 dx = 0 dy = 0 k = 0 else x=x+dx
    y=y+dy end
end

function touched(touch)
        if touch.state == BEGAN then
            k = k + 1
            if k == 1 then
            dx=2 --the amount x changes
            dy=2 --the amount y changes
            score = score + 2
            end
        if touch.state == MOVING or touch.state == BEGAN and k > 1 then
            if dx > 0 then
            dx= math.random(-6, -2) --the amount x changes
            dy= math.random(-6, -2) --the amount y changes
            score = score + 1
            elseif dx < 0 then
            dx=math.random(2,6)
            dy=math.random(2,6)
            end
            if y > 619 or y < 101 then
                score = score + math.random(8,11)
            elseif x > 619 or x < 101 then
                score = score + math.random(8,11)
            end
            end
        end
end