CC Bloons Tower Defense

local w,h = term.getSize()
local previous = {0,math.floor(h/2)}
local entry = {1,math.floor(h/2)}
local exit = {w,math.floor(h/2)}


local buffer = {}
for x = 1,w do
    buffer[x] = {}
    for y = 1,h do
        buffer[x][y] = nil
    end
end


for x= 1, w do
    buffer[x][math.floor(h/2)] = {char=" ",track=true,backcol=colors.orange}
end

function Balloon(layer, delay)
    local balloon = {}
    balloon.speed = layer
    balloon.layer = layer
    balloon.delay = delay
    balloon.pos = entry
    balloon.previous = previous
    balloon.dir = "east"
    if layer == 1 then
        balloon.color = colors.red
    elseif layer == 2 then
        balloon.color = colors.blue
    elseif layer == 3 then
        balloon.color = colors.green
    end
    return balloon
end


bloons = {
red = Balloon(1,0),
red2 = Balloon(1,2),
blue = Balloon(2,4),
green = Balloon(3,7),
}

ntime = 0

for x=1,w do
    for y=1,h do
        if buffer[x][y] then
            term.setBackgroundColor(buffer[x][y].backcol)
            term.setCursorPos(x,y)
            term.write(buffer[x][y].char)
        end
    end
end

while true do
    for _,bloon in pairs(bloons) do
        if ntime >= bloon.delay then
            term.setCursorPos(bloon.pos[1],bloon.pos[2])
            term.setBackgroundColor(bloon.color)
            term.write(" ")
            term.setBackgroundColor(colors.orange)
            term.setCursorPos(bloon.previous[1],bloon.previous[2])
            term.write(" ")
            bloon.previous[1],bloon.previous[2] = bloon.pos[1],bloon.pos[2]
            if bloon.dir == "east" then
                bloon.pos[1] = bloon.pos[1] + 1
            end
        end
    end
    sleep(1)
    ntime = ntime + 1
end