Implementation of 2048 with OctaForge UI.

octa2048.lua

local genblock = |val, color, tcolor| || gui.Color_Filler {
    color = color, min_w = 0.18, min_h = 0.18,
    gui.Label {
        text = tostring(val), scale = 3.5, color = tcolor
    }
}

local blocktypes = {
    [0] = || gui.Color_Filler {
        color = 0xccc0b3, min_w = 0.18, min_h = 0.18
    },
    [2   ] = genblock(2,    0xEEE4DA, 0x776E65),
    [4   ] = genblock(4,    0xEDE0C8, 0x776E65),
    [8   ] = genblock(8,    0xF2B179, 0xF9F6F2),
    [16  ] = genblock(16,   0xF59563, 0xF9F6F2),
    [32  ] = genblock(32,   0xF67C5F, 0xF9F6F2),
    [64  ] = genblock(64,   0xF65E3B, 0xF9F6F2),
    [128 ] = genblock(128,  0xEDCF72, 0xF9F6F2),
    [256 ] = genblock(256,  0xEDCC61, 0xF9F6F2),
    [512 ] = genblock(512,  0xEDC850, 0xF9F6F2),
    [1024] = genblock(1024, 0xEDC53F, 0xF9F6F2),
    [2048] = genblock(2048, 0xEDC22E, 0xF9F6F2),
    [4096] = genblock(4096, 0x3C3A32, 0xF9F6F2)
}

local tiles   = {}
local cleanup = {}

local totalscore = 0

local cleanuptiles = || do
    for i, v in ipairs(cleanup) do cleanup[i]:destroy() end
end

local seedtiles = || do
    local t1, t2 = math.random(1, 16)
    repeat t2 = math.random(1, 16) until t2 != t1
    local vals = { 2, 4 }
    local tv1, tv2 = vals[math.random(1, 2)],
                     vals[math.random(1, 2)]
    for i = 1, 16 do
        if i == t1 then
            tiles[i] = tv1
        elseif i == t2 then
            tiles[i] = tv2
        else
            tiles[i] = 0
        end
    end
end

local randtile = |grid| do
    local emptyfields = {}
    for i = 1, 16 do
        if tiles[i] == 0 then emptyfields[#emptyfields + 1] = i end
    end
    if #emptyfields == 0 then return end
    local n = emptyfields[math.random(1, #emptyfields)]
    tiles[n] = ({ 2, 4 })[math.random(1, 2)]
    grid:remove(n)
    grid:insert(n, blocktypes[tiles[n]]())
    if #emptyfields == 1 then
        -- check game over (yes if nothing is mergeable)
        local gameover = true
        for a = 1, 2 do
            local ia, ib, ic, ja, jb, jc
            if a == 1 then
                ia, ib, ic = 0, 12, 4
                ja, jb, jc = 1, 3, 1
            else
                ia, ib, ic = 0, 3, 1
                ja, jb, jc = 1, 13, 4
            end
            for i = ia, ib, ic do
                for j = ja + i, jb + i, jc do
                    if tiles[j] == tiles[j + 1] then
                        gameover = false
                        break
                    end
                end
                if not gameover then break end
            end
            if not gameover then break end
        end
        if gameover then totalscore = -totalscore end
    end
end

local pendinganims = 0

local guimovetile = |grid, i, j, step, hdir, vdir| do
    local o = grid:remove(j, true)
    local oadj = o.adjust
    grid:insert(j, blocktypes[0]())
    local n = (j - i) / step
    local dist = 0.205 * n
    local dirn, mspeed, dx, dy
    if hdir != 0 then
        dirn, mspeed = "speedup,x", 3 * n * hdir
        dx, dy = dist, 0
    else
        dirn, mspeed = "speedup,y", 3 * n * vdir
        dx, dy = 0, dist
    end
    grid.parent:append(gui.Auto_Mover {
        move_func = dirn, move_speed = mspeed,
        move_dist_x = dx, move_dist_y = dy, o
    }, |m| do
        m:clamp(true, true, true, true)
        connect(m, "anim,start", || do
            pendinganims += 1
        end)
        connect(m, "anim,end", || do
            m:set_visible(false)
            cleanup[#cleanup + 1] = m
            grid:remove(i)
            grid:insert(i, blocktypes[tiles[i]]())
            pendinganims -= 1
            if pendinganims == 0 then
                randtile(grid)
            end
            grid:layout()
        end)
        m:start()
        grid.parent:append(m)
    end)
    o.floating = true
    o.adjust   = 0
end

local movetile = |grid, off, hdir, vdir| do
    local dir = (hdir != 0) and hdir or (vdir * 4)
    local lbeg, lend, lstart
    if dir < 0 then
        if hdir != 0 then
            lbeg, lend, lstart = 2, 4, 1
        else
            lbeg, lend, lstart = 5, 13, 1
        end
    else
        if hdir != 0 then
            lbeg, lend, lstart = 3, 1, 4
        else
            lbeg, lend, lstart = 9, 1, 13
        end
    end
    local jm = false
    for i = lbeg, lend, -dir do
        local nnz
        for j = i + dir, lstart, dir do
            if tiles[j + off] != 0 then
                nnz = j
                break
            end
        end
        if nnz and not jm and tiles[nnz + off] == tiles[i + off] then
            jm = true
            tiles[nnz + off] += tiles[i + off]
            tiles[i + off] = 0
            guimovetile(grid, nnz + off, i + off, -dir, hdir, vdir)
            totalscore += tiles[nnz + off]
        elseif tiles[i + off] != 0 then
            jm = false
            local fz
            for j = i + dir, lstart, dir do
                if tiles[j + off] == 0 then fz = j end
            end
            if fz then
                tiles[fz + off] = tiles[i + off]
                tiles[i + off] = 0
                guimovetile(grid, fz + off, i + off, -dir, hdir, vdir)
            end
        end
    end
end

local movetiles = |grid, h, v| do
    if h != 0 then
        movetile(grid, 0,  h, 0)
        movetile(grid, 4,  h, 0)
        movetile(grid, 8,  h, 0)
        movetile(grid, 12, h, 0)
    end
    if v != 0 then
        movetile(grid, 0, 0, v)
        movetile(grid, 1, 0, v)
        movetile(grid, 2, 0, v)
        movetile(grid, 3, 0, v)
    end
    cleanuptiles()
end

local seededtiles = false
world:new_window("2048", gui.Window, |win| do
    win:set_floating(true)
    win:set_variant("movable")
    win:set_title("2048 (score: 0)")
    connect(win, "destroy", || do totalscore = 0 end)
    win:append(gui.Color_Filler { color = 0xBBADA0 }, |cf| do
        cf:clamp(true, true, true, true)
        win:append(gui.Spacer { pad_h = 0.025, pad_v = 0.025 }, |sp| do
            sp:append(gui.Grid { columns = 4, padding = 0.025 }, |grid| do
                cf.key = function(self, code, isdown)
                    if isdown then
                        if code == gui.key.LEFT then
                            movetiles(grid, -1,  0)
                        elseif code == gui.key.RIGHT then
                            movetiles(grid,  1,  0)
                        elseif code == gui.key.UP then
                            movetiles(grid,  0, -1)
                        elseif code == gui.key.DOWN then
                            movetiles(grid,  0,  1)
                        end
                    end
                    if totalscore < 0 then
                        win:set_title(("2048 (game over, last score: %d)"
                            ):format(-totalscore))
                        cf.key = nil
                    else
                        win:set_title(("2048 (score: %d)"):format(totalscore))
                    end
                    return gui.Widget.key(self, code, isdown)
                end
                if totalscore < 0 then
                    totalscore, seededtiles, tiles = 0, false, {}
                end
                if not seededtiles then
                    seedtiles()
                    seededtiles = true
                end
                for i = 1, #tiles do
                    grid:append(blocktypes[tiles[i]]())
                end
            end)
        end)
    end)
end)