diff --git a/deploy/apps/2048/1.2/2048.json b/deploy/apps/2048/1.2/2048.json
new file mode 100644
index 0000000..6c2778b
--- /dev/null
+++ b/deploy/apps/2048/1.2/2048.json
@@ -0,0 +1 @@
+{"id":"2048","name":"2048","ver":"1.2","desc":"The classic sliding-tile puzzle. Swipe to move, tap to restart. Keeps your best score. Contributed by pisti87."}
diff --git a/deploy/apps/2048/1.2/2048.lua b/deploy/apps/2048/1.2/2048.lua
new file mode 100644
index 0000000..891c879
--- /dev/null
+++ b/deploy/apps/2048/1.2/2048.lua
@@ -0,0 +1,837 @@
+-- 2048 — wada.* reference app
+-- Swipe (or trackball mapped swipe) to move tiles.
+-- Tap after win or game over to restart.
+
+local ui, sys, store, timer = wada.ui, wada.sys, wada.store, wada.timer
+local C = ui.colors
+
+local app = {}
+
+local cv, score_lbl
+
+local CELL = 38
+
+local grid = {}
+
+local history = {
+    grids = {},
+    maxsize = 5
+}
+
+local px_w, px_h
+local score = 0
+local hiscore = 0
+
+local over = false
+local won = false
+
+
+--------------------------------------------------
+-- History
+--------------------------------------------------
+
+function history:save()
+
+    local old = {
+        grid = {},
+        score = score,
+        over = over,
+        won = won
+    }
+
+    for x = 1, 4 do
+
+        old.grid[x] = {}
+
+        for y = 1, 4 do
+            old.grid[x][y] = grid[x][y]
+        end
+
+    end
+
+    table.insert(self.grids, old)
+
+    if #self.grids > self.maxsize then
+        table.remove(self.grids, 1)
+    end
+
+end
+
+
+function history:revert()
+
+    if #self.grids > 0 then
+
+        local old = table.remove(self.grids)
+
+        grid = old.grid
+        score = old.score
+        over = old.over
+        won = old.won
+
+    end
+
+end
+
+
+--------------------------------------------------
+-- Game logic
+--------------------------------------------------
+
+local function clear_grid()
+
+    grid = {}
+
+    for x = 1, 4 do
+
+        grid[x] = {}
+
+        for y = 1, 4 do
+            grid[x][y] = 0
+        end
+
+    end
+
+end
+
+
+--------------------------------------------------
+-- Add random tile
+--------------------------------------------------
+
+local function add_random_tile()
+
+    local free = {}
+
+    for x = 1, 4 do
+
+        for y = 1, 4 do
+
+            if grid[x][y] == 0 then
+
+                table.insert(
+                    free,
+                    {
+                        x = x,
+                        y = y
+                    }
+                )
+
+            end
+
+        end
+
+    end
+
+
+    -- Board is full.
+    if #free == 0 then
+        return false
+    end
+
+
+    local p
+
+
+    -- If there is only one empty cell,
+    -- use it directly.
+    if #free == 1 then
+
+        p = free[1]
+
+    else
+
+        local index = sys.random(1, #free)
+
+        if index == nil then
+            return false
+        end
+
+        p = free[index]
+
+        if p == nil then
+            return false
+        end
+
+    end
+
+
+    -- 10% chance for 4,
+    -- 90% chance for 2.
+    if sys.random(0, 9) == 0 then
+        grid[p.x][p.y] = 4
+    else
+        grid[p.x][p.y] = 2
+    end
+
+    return true
+
+end
+
+
+--------------------------------------------------
+-- Reset
+--------------------------------------------------
+
+local function reset()
+
+    clear_grid()
+
+    score = 0
+    over = false
+    won = false
+
+    history.grids = {}
+
+    add_random_tile()
+    add_random_tile()
+
+end
+
+
+--------------------------------------------------
+-- Compress line
+--------------------------------------------------
+
+local function compress(line)
+
+    local r = {}
+
+    for i = 1, 4 do
+
+        if line[i] ~= 0 then
+            table.insert(r, line[i])
+        end
+
+    end
+
+    while #r < 4 do
+        table.insert(r, 0)
+    end
+
+    return r
+
+end
+
+
+--------------------------------------------------
+-- Merge line
+--------------------------------------------------
+
+local function merge(line)
+
+    local r = {}
+    local i = 1
+
+    while i <= 4 do
+
+        if i < 4
+            and line[i] ~= 0
+            and line[i] == line[i + 1]
+        then
+
+            local v = line[i] * 2
+
+            table.insert(r, v)
+
+            score = score + v
+
+
+            -- Permanent high score.
+            if score > hiscore then
+
+                hiscore = score
+
+                store.set(
+                    "2048_best",
+                    hiscore
+                )
+
+            end
+
+
+            -- Reaching 2048 means victory.
+            if v >= 2048 then
+                won = true
+            end
+
+
+            i = i + 2
+
+        else
+
+            table.insert(r, line[i])
+
+            i = i + 1
+
+        end
+
+    end
+
+
+    while #r < 4 do
+        table.insert(r, 0)
+    end
+
+    return r
+
+end
+
+
+--------------------------------------------------
+-- Move left
+--------------------------------------------------
+
+local function move_left()
+
+    local changed = false
+
+    for y = 1, 4 do
+
+        local old = {}
+        local line = {}
+
+        for x = 1, 4 do
+
+            old[x] = grid[x][y]
+            line[x] = grid[x][y]
+
+        end
+
+
+        line = compress(line)
+        line = merge(line)
+
+
+        for x = 1, 4 do
+
+            grid[x][y] = line[x]
+
+            if old[x] ~= line[x] then
+                changed = true
+            end
+
+        end
+
+    end
+
+    return changed
+
+end
+
+
+--------------------------------------------------
+-- Rotate
+--------------------------------------------------
+
+local function rotate()
+
+    local n = {}
+
+    for x = 1, 4 do
+        n[x] = {}
+    end
+
+
+    for x = 1, 4 do
+
+        for y = 1, 4 do
+
+            n[y][5 - x] = grid[x][y]
+
+        end
+
+    end
+
+
+    grid = n
+
+end
+
+
+--------------------------------------------------
+-- Game over
+--------------------------------------------------
+
+local function game_over()
+
+    -- Any empty cell means the game can continue.
+    for x = 1, 4 do
+
+        for y = 1, 4 do
+
+            if grid[x][y] == 0 then
+                return false
+            end
+
+        end
+
+    end
+
+
+    -- Check horizontal and vertical merges.
+    for x = 1, 4 do
+
+        for y = 1, 4 do
+
+            if x < 4
+                and grid[x][y] == grid[x + 1][y]
+            then
+                return false
+            end
+
+
+            if y < 4
+                and grid[x][y] == grid[x][y + 1]
+            then
+                return false
+            end
+
+        end
+
+    end
+
+
+    -- Board is full and no merge is possible.
+    return true
+
+end
+
+
+--------------------------------------------------
+-- Move
+--------------------------------------------------
+
+local function move(dir)
+
+    -- Do nothing after victory or defeat.
+    if over or won then
+        return
+    end
+
+
+    history:save()
+
+    local changed = false
+
+
+    if dir == "left" then
+
+        changed = move_left()
+
+
+    elseif dir == "right" then
+
+        rotate()
+        rotate()
+
+        changed = move_left()
+
+        rotate()
+        rotate()
+
+
+    elseif dir == "up" then
+
+        rotate()
+
+        changed = move_left()
+
+        rotate()
+        rotate()
+        rotate()
+
+
+    elseif dir == "down" then
+
+        rotate()
+        rotate()
+        rotate()
+
+        changed = move_left()
+
+        rotate()
+
+    end
+
+
+    --------------------------------------------------
+    -- Nothing moved.
+    --------------------------------------------------
+
+    if not changed then
+
+        history:revert()
+
+        return
+
+    end
+
+
+    --------------------------------------------------
+    -- Successful move.
+    -- Exactly one new tile must be created.
+    --------------------------------------------------
+
+    local added = add_random_tile()
+
+
+    --------------------------------------------------
+    -- This should only happen if the board was already
+    -- completely full. Normally a successful move on a
+    -- full board creates space, so added should be true.
+    --------------------------------------------------
+
+    if not added then
+
+        over = true
+
+        return
+
+    end
+
+
+    --------------------------------------------------
+    -- Victory.
+    --
+    -- merge() sets won when a 2048 tile is created.
+    --------------------------------------------------
+
+    if won then
+        return
+    end
+
+
+    --------------------------------------------------
+    -- IMPORTANT:
+    --
+    -- Game-over is checked AFTER the new random tile
+    -- has been inserted.
+    --------------------------------------------------
+
+    if game_over() then
+        over = true
+    end
+
+end
+
+
+--------------------------------------------------
+-- Tile colors
+--------------------------------------------------
+
+local function tile_color(v)
+
+    if v == 0 then
+        return 0xCDC1B4
+
+    elseif v == 2 then
+        return 0xEEE4DA
+
+    elseif v == 4 then
+        return 0xEDE0C8
+
+    elseif v == 8 then
+        return 0xF2B179
+
+    elseif v == 16 then
+        return 0xF59563
+
+    elseif v == 32 then
+        return 0xF67C5F
+
+    elseif v == 64 then
+        return 0xF65E3B
+
+    elseif v == 128 then
+        return 0xEDCF72
+
+    elseif v == 256 then
+        return 0xEDCC61
+
+    elseif v == 512 then
+        return 0xEDC850
+
+    elseif v == 1024 then
+        return 0xEDC53F
+
+    elseif v == 2048 then
+        return 0xEDC22E
+
+    end
+
+    -- Values above 2048.
+    return 0x3C3A32
+
+end
+
+
+--------------------------------------------------
+-- Text colors
+--------------------------------------------------
+
+local function text_color(v)
+
+    if v <= 4 then
+        return 0x776E65
+    else
+        return 0xFFFFFF
+    end
+
+end
+
+
+--------------------------------------------------
+-- Text size
+--------------------------------------------------
+
+local function text_size(v)
+
+    if v < 100 then
+        return 16
+
+    elseif v < 1000 then
+        return 14
+
+    elseif v < 10000 then
+        return 11
+
+    else
+        return 9
+    end
+
+end
+
+
+--------------------------------------------------
+-- Text positioning
+--------------------------------------------------
+
+local function text_x(px, v, size)
+
+    local width
+
+    if v < 100 then
+        width = size * 1.1
+
+    elseif v < 1000 then
+        width = size * 1.7
+
+    elseif v < 10000 then
+        width = size * 2.3
+
+    else
+        width = size * 2.9
+    end
+
+
+    return px + math.floor(
+        (CELL - width) / 2
+    )
+
+end
+
+
+local function text_y(py, size)
+
+    return py + math.floor(
+        (CELL - size) / 2
+    )
+
+end
+
+
+--------------------------------------------------
+-- Score line
+--------------------------------------------------
+
+local function scoreline()
+
+    local status = ""
+
+    if won then
+
+        status = "   - tap retry"
+
+    elseif over then
+
+        status = "   - tap retry"
+
+    end
+
+
+    score_lbl:set(
+        string.format(
+            "Score %d   Best %d%s",
+            score,
+            hiscore,
+            status
+        )
+    )
+
+end
+
+
+--------------------------------------------------
+-- Draw
+--------------------------------------------------
+
+local function draw()
+
+    cv:fill(0x101418)
+
+
+    for x = 1, 4 do
+
+        for y = 1, 4 do
+
+            local px = (x - 1) * CELL
+            local py = (y - 1) * CELL
+
+            local v = grid[x][y]
+
+
+            cv:rect(
+                px + 2,
+                py + 2,
+                CELL - 4,
+                CELL - 4,
+                tile_color(v),
+                true,
+                4
+            )
+
+
+            if v > 0 then
+
+                local size = text_size(v)
+
+                cv:text(
+                    text_x(px, v, size),
+                    text_y(py, size),
+                    tostring(v),
+                    text_color(v),
+                    size
+                )
+
+            end
+
+        end
+
+    end
+
+
+    --------------------------------------------------
+    -- End messages
+    --------------------------------------------------
+
+    if won then
+
+        cv:text(
+            30,
+            px_h / 2,
+            "YOU WIN!",
+            C.good,
+            18
+        )
+
+    elseif over then
+
+        cv:text(
+            30,
+            px_h / 2,
+            "GAME OVER",
+            C.bad,
+            18
+        )
+
+    end
+
+end
+
+
+--------------------------------------------------
+-- WADAMESH API
+--------------------------------------------------
+
+function app.on_open(w, h)
+
+    hiscore = store.get(
+        "2048_best",
+        0
+    )
+
+
+    px_w = CELL * 4
+    px_h = CELL * 4
+
+
+    score_lbl = ui.label(
+        "",
+        4,
+        4,
+        14,
+        C.text
+    )
+
+
+    cv = ui.canvas(
+        px_w,
+        px_h
+    )
+
+
+    cv:pos(
+        math.floor(
+            (w - px_w) / 2
+        ),
+        28
+    )
+
+
+    reset()
+
+    scoreline()
+    draw()
+
+
+    timer.every(100)
+
+end
+
+
+function app.on_input(ev)
+
+    if ev.type == "swipe" then
+
+        move(ev.dir)
+
+        scoreline()
+        draw()
+
+
+    elseif ev.type == "down"
+        and (over or won)
+    then
+
+        reset()
+
+        scoreline()
+        draw()
+
+    end
+
+end
+
+
+function app.on_tick(dt)
+
+end
+
+
+function app.on_close()
+
+end
+
+
+return app
diff --git a/deploy/apps/apps.json b/deploy/apps/apps.json
index 5315bf0..dab18cf 100644
--- a/deploy/apps/apps.json
+++ b/deploy/apps/apps.json
@@ -1,6 +1,34 @@
-{"apps":[
-  {"id":"monitor","name":"RF Monitor","ver":"1.3","desc":"Scrollable: RSSI/noise chart with dBm axis, link margin, RX rate, radio params, heard feed."},
-  {"id":"airtime","name":"Airtime","ver":"1.3","desc":"Utilization bars with a % axis, rx/tx split, duty ceiling, budget. Reset button top-right."},
-  {"id":"snake","name":"Snake","ver":"1.0","desc":"The classic, in Lua. Swipe to steer."},
-  {"id":"sdktest","name":"SDK Test","ver":"1.1","desc":"Developer tool. Checks the extended Lua SDK on this board: capabilities, clock, battery, GPS, file access and its limits, keyboard input. Has a button that TRANSMITS a test message to Public (asks permission first)."}
-]}
+{
+  "apps": [
+    {
+      "id": "monitor",
+      "name": "RF Monitor",
+      "ver": "1.3",
+      "desc": "Scrollable: RSSI/noise chart with dBm axis, link margin, RX rate, radio params, heard feed."
+    },
+    {
+      "id": "airtime",
+      "name": "Airtime",
+      "ver": "1.3",
+      "desc": "Utilization bars with a % axis, rx/tx split, duty ceiling, budget. Reset button top-right."
+    },
+    {
+      "id": "snake",
+      "name": "Snake",
+      "ver": "1.0",
+      "desc": "The classic, in Lua. Swipe to steer."
+    },
+    {
+      "id": "sdktest",
+      "name": "SDK Test",
+      "ver": "1.1",
+      "desc": "Developer tool. Checks the extended Lua SDK on this board: capabilities, clock, battery, GPS, file access and its limits, keyboard input. Has a button that TRANSMITS a test message to Public (asks permission first)."
+    },
+    {
+      "id": "2048",
+      "name": "2048",
+      "ver": "1.2",
+      "desc": "The classic sliding-tile puzzle. Swipe to move, tap to restart. Keeps your best score. Contributed by pisti87."
+    }
+  ]
+}
diff --git a/scripts/deploy-apps.sh b/scripts/deploy-apps.sh
index d5b9fb5..602b195 100755
--- a/scripts/deploy-apps.sh
+++ b/scripts/deploy-apps.sh
@@ -44,8 +44,19 @@ missing = [f"{l['code']} v{l['ver']}" for l in langs
            if not os.path.isfile(os.path.join(apps_dir, "lang", str(l["ver"]), l["code"] + ".lang"))]
 if missing:
     sys.exit("ABORT: langs.json points at files that do not exist: " + ", ".join(missing))
-json.load(open(os.path.join(apps_dir, "apps.json")))          # parse check
-print(f"catalogs ok: {len(langs)} languages, every referenced .lang present")
+
+# Same check for apps: an entry whose <id>/<ver>/<id>.lua is absent shows up in the
+# Store and then fails to install, with nothing on screen to say why.
+apps = json.load(open(os.path.join(apps_dir, "apps.json")))["apps"]
+bad = []
+for a in apps:
+    base = os.path.join(apps_dir, a["id"], a["ver"])
+    for f in (a["id"] + ".lua", a["id"] + ".json"):
+        if not os.path.isfile(os.path.join(base, f)):
+            bad.append(f'{a["id"]} v{a["ver"]}: {f}')
+if bad:
+    sys.exit("ABORT: apps.json points at files that do not exist: " + ", ".join(bad))
+print(f"catalogs ok: {len(langs)} languages and {len(apps)} apps, every referenced file present")
 PY
 
 # --delete mirrors the repo: the store is generated content, the repo is the source