diff --git a/badge/apps/mona_slice/README.md b/badge/apps/mona_slice/README.md
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+++ b/badge/apps/mona_slice/README.md
@@ -0,0 +1,11 @@
+# Mona Slice
+
+Claim cozy corners by carving the playfield while keeping Mona and her friends safe.
+
+## Usage
+
+Move the cursor with the arrows, press Select to start a cut, and press Back to switch between horizontal and vertical cuts; the slicer marker shows the selected direction. The cursor can move anywhere, and a cut started in claimed territory travels through it into open space; once in open space, each end stops independently at the next wall, claimed area, or edge. Claim at least 75% of the field before losing all three paws. Mona's animated sprite always faces left or right, following her horizontal movement. Clear a level to meet more Monas, up to five, and face faster movement. Press Select to begin, continue, or replay. No extra hardware or network access is required.
+
+## Credits
+
+Mona sprite sheet and icon are reused from this repository's `flappy_mona` app; `assets/mona_left.png` is a horizontally mirrored copy.
diff --git a/badge/apps/mona_slice/__init__.py b/badge/apps/mona_slice/__init__.py
new file mode 100644
index 00000000..1596b09b
--- /dev/null
+++ b/badge/apps/mona_slice/__init__.py
@@ -0,0 +1,466 @@
+import os
+import sys
+
+APP_DIR = "/system/apps/mona_slice"
+os.chdir(APP_DIR)
+sys.path.insert(0, APP_DIR)
+
+from badgeware import State
+
+badge.mode(HIRES | VSYNC)
+screen.font = font.nope
+
+GRID_W = 36
+GRID_H = 20
+CELL = 8
+BOARD_X = 16
+BOARD_Y = 42
+BOARD_W = GRID_W * CELL
+BOARD_H = GRID_H * CELL
+BALL_R = 6
+SPRITE_HALF = 12
+GOAL = 75
+MAX_MONAS = 5
+CUT_SPEED = 28
+CURSOR_REPEAT = 0.085
+
+INK = color.rgb(20, 15, 41)
+PANEL = color.rgb(38, 25, 67)
+FIELD = color.rgb(20, 13, 37)
+MINT = color.rgb(112, 255, 215)
+PINK = color.rgb(255, 124, 201)
+LAVENDER = color.rgb(171, 135, 255)
+WHITE = color.rgb(255, 240, 255)
+GOLD = color.rgb(255, 220, 112)
+
+mona_sprites = image.load("assets/mona.png").spritesheet(7, 2)
+mona_left_sprites = image.load("assets/mona_left.png").spritesheet(7, 2)
+best = {"percent": 0, "level": 1}
+State.load("mona_slice", best)
+
+state = "title"
+grid = []
+walls = []
+monas = []
+level = 1
+cursor_x = GRID_W // 2
+cursor_y = GRID_H // 2
+cut_axis = "horizontal"
+cut = None
+lives = 3
+percent = 0
+cuts = 0
+repeat_timer = 0
+
+
+def new_game():
+    global lives, level
+
+    lives = 3
+    level = 1
+    start_level(level)
+
+
+def start_level(next_level):
+    global state, grid, walls, monas, cursor_x, cursor_y, cut_axis, cut
+    global percent, cuts, level
+
+    level = next_level
+    grid = [[False for _ in range(GRID_W)] for _ in range(GRID_H)]
+    walls = [[False for _ in range(GRID_W)] for _ in range(GRID_H)]
+    speed = 1 + min(level - 1, 8) * 0.1
+    starts = (
+        (0.43, 0.53, 49, 34),
+        (0.68, 0.35, -38, 46),
+        (0.30, 0.72, 54, -37),
+        (0.74, 0.70, -43, -52),
+        (0.49, 0.27, 61, 42),
+    )
+    monas = []
+    for x, y, vx, vy in starts[:min(level, MAX_MONAS)]:
+        monas.append({
+            "x": BOARD_X + BOARD_W * x,
+            "y": BOARD_Y + BOARD_H * y,
+            "vx": vx * speed,
+            "vy": vy * speed,
+        })
+    cursor_x = GRID_W // 2
+    cursor_y = GRID_H // 2
+    cut_axis = "horizontal"
+    cut = None
+    percent = 0
+    cuts = 0
+    state = "playing"
+
+
+def blocked_at(x, y):
+    gx = int((x - BOARD_X) // CELL)
+    gy = int((y - BOARD_Y) // CELL)
+    if gx < 0 or gx >= GRID_W or gy < 0 or gy >= GRID_H:
+        return True
+    return grid[gy][gx]
+
+
+def update_ball(mona, dt):
+    for axis in ("x", "y"):
+        position_key = axis
+        velocity_key = "v" + axis
+        if axis == "x":
+            minimum = BOARD_X + SPRITE_HALF
+            maximum = BOARD_X + BOARD_W - SPRITE_HALF
+        else:
+            minimum = BOARD_Y + SPRITE_HALF
+            maximum = BOARD_Y + BOARD_H - SPRITE_HALF
+
+        remaining = abs(mona[velocity_key] * dt)
+        while remaining > 0:
+            distance = min(1, remaining)
+            direction = 1 if mona[velocity_key] > 0 else -1
+            next_position = mona[position_key] + direction * distance
+            if axis == "x":
+                blocked = blocked_at(next_position + BALL_R * direction, mona["y"])
+            else:
+                blocked = blocked_at(mona["x"], next_position + BALL_R * direction)
+
+            if next_position < minimum or next_position > maximum:
+                mona[position_key] = max(minimum, min(maximum, next_position))
+                mona[velocity_key] = -mona[velocity_key]
+            elif blocked:
+                reverse_position = mona[position_key] - direction * distance
+                if axis == "x":
+                    reverse_blocked = blocked_at(
+                        reverse_position - BALL_R * direction, mona["y"]
+                    )
+                else:
+                    reverse_blocked = blocked_at(
+                        mona["x"], reverse_position - BALL_R * direction
+                    )
+                if not reverse_blocked:
+                    mona[velocity_key] = -mona[velocity_key]
+            else:
+                mona[position_key] = next_position
+            remaining -= distance
+
+
+def move_cursor():
+    direction = None
+    if badge.held(BUTTON_LEFT):
+        direction = (-1, 0)
+    elif badge.held(BUTTON_RIGHT):
+        direction = (1, 0)
+    elif badge.held(BUTTON_UP):
+        direction = (0, -1)
+    elif badge.held(BUTTON_DOWN):
+        direction = (0, 1)
+
+    if direction is None:
+        advance_cursor(None, 0)
+        return
+
+    advance_cursor(direction, badge.ticks_delta / 1000)
+
+
+def advance_cursor(direction, elapsed):
+    global cursor_x, cursor_y, repeat_timer
+
+    if direction is None:
+        repeat_timer = 0
+        return
+
+    repeat_timer -= elapsed
+    while repeat_timer <= 0:
+        cursor_x = max(0, min(GRID_W - 1, cursor_x + direction[0]))
+        cursor_y = max(0, min(GRID_H - 1, cursor_y + direction[1]))
+        repeat_timer += CURSOR_REPEAT
+
+
+def cell_blocked(x, y):
+    return grid[y][x] or walls[y][x]
+
+
+def cut_extent(dx, dy):
+    # Pass through captured cells until open space is reached, then stop at the next blocker.
+    seen_open = not cell_blocked(cursor_x, cursor_y)
+    step = 1
+    while True:
+        x = cursor_x + dx * step
+        y = cursor_y + dy * step
+        if x < 0 or x >= GRID_W or y < 0 or y >= GRID_H:
+            return step - 0.5 if seen_open else 0
+        if cell_blocked(x, y):
+            if seen_open:
+                return step - 0.5
+        else:
+            seen_open = True
+        step += 1
+
+
+def start_cut():
+    global cut
+
+    if cut_axis == "horizontal":
+        negative = cut_extent(-1, 0)
+        positive = cut_extent(1, 0)
+    else:
+        negative = cut_extent(0, -1)
+        positive = cut_extent(0, 1)
+    if negative <= 0 and positive <= 0:
+        return
+    cut = {
+        "axis": cut_axis,
+        "negative": negative,
+        "positive": positive,
+        "negative_length": 0,
+        "positive_length": 0,
+    }
+
+
+def cut_hits_mona(negative_length, positive_length, mona):
+    center_x = BOARD_X + cursor_x * CELL + CELL / 2
+    center_y = BOARD_Y + cursor_y * CELL + CELL / 2
+    if cut["axis"] == "horizontal":
+        along = mona["x"] - center_x
+        return (
+            abs(mona["y"] - center_y) <= BALL_R + 2
+            and -negative_length * CELL - BALL_R <= along <= positive_length * CELL + BALL_R
+        )
+    along = mona["y"] - center_y
+    return (
+        abs(mona["x"] - center_x) <= BALL_R + 2
+        and -negative_length * CELL - BALL_R <= along <= positive_length * CELL + BALL_R
+    )
+
+
+def fill_regions():
+    global percent
+
+    visited = [[False for _ in range(GRID_W)] for _ in range(GRID_H)]
+    queue = []
+    for mona in monas:
+        start_x = max(0, min(GRID_W - 1, int((mona["x"] - BOARD_X) // CELL)))
+        start_y = max(0, min(GRID_H - 1, int((mona["y"] - BOARD_Y) // CELL)))
+        if not grid[start_y][start_x] and not walls[start_y][start_x] and not visited[start_y][start_x]:
+            queue.append(start_y * GRID_W + start_x)
+            visited[start_y][start_x] = True
+
+    index = 0
+    while index < len(queue):
+        cell = queue[index]
+        index += 1
+        x = cell % GRID_W
+        y = cell // GRID_W
+        for nx, ny in ((x - 1, y), (x + 1, y), (x, y - 1), (x, y + 1)):
+            if (
+                0 <= nx < GRID_W
+                and 0 <= ny < GRID_H
+                and not grid[ny][nx]
+                and not walls[ny][nx]
+                and not visited[ny][nx]
+            ):
+                visited[ny][nx] = True
+                queue.append(ny * GRID_W + nx)
+
+    filled = 0
+    for y in range(GRID_H):
+        for x in range(GRID_W):
+            if not visited[y][x] and not walls[y][x]:
+                grid[y][x] = True
+            if grid[y][x] or walls[y][x]:
+                filled += 1
+    percent = int(filled * 100 / (GRID_W * GRID_H))
+
+
+def finish_cut():
+    global cut, cuts, state, best
+
+    negative_cells = int(cut["negative"])
+    positive_cells = int(cut["positive"])
+    if cut["axis"] == "horizontal":
+        for x in range(cursor_x - negative_cells, cursor_x + positive_cells + 1):
+            walls[cursor_y][x] = True
+            grid[cursor_y][x] = True
+    else:
+        for y in range(cursor_y - negative_cells, cursor_y + positive_cells + 1):
+            walls[y][cursor_x] = True
+            grid[y][cursor_x] = True
+    cut = None
+    cuts += 1
+    fill_regions()
+    if percent >= GOAL:
+        state = "level_clear"
+        if level > best["level"]:
+            best["level"] = level
+            State.save("mona_slice", best)
+
+
+def update_cut(dt):
+    global cut, lives, state
+
+    cut["negative_length"] = min(
+        cut["negative"],
+        cut["negative_length"] + CUT_SPEED * dt,
+    )
+    cut["positive_length"] = min(
+        cut["positive"],
+        cut["positive_length"] + CUT_SPEED * dt,
+    )
+    for mona in monas:
+        if cut_hits_mona(cut["negative_length"], cut["positive_length"], mona):
+            cut = None
+            lives -= 1
+            if lives <= 0:
+                state = "lost"
+            return
+    if (
+        cut["negative_length"] >= cut["negative"]
+        and cut["positive_length"] >= cut["positive"]
+    ):
+        finish_cut()
+
+
+def draw_board():
+    screen.pen = PANEL
+    screen.shape(shape.rounded_rectangle(BOARD_X - 3, BOARD_Y - 3, BOARD_W + 6, BOARD_H + 6, 5))
+    screen.pen = FIELD
+    screen.shape(shape.rectangle(BOARD_X, BOARD_Y, BOARD_W, BOARD_H))
+
+    for y in range(GRID_H):
+        for x in range(GRID_W):
+            if grid[y][x]:
+                screen.pen = LAVENDER if (x + y) % 4 else PINK
+                screen.shape(shape.rectangle(BOARD_X + x * CELL, BOARD_Y + y * CELL, CELL, CELL))
+
+    if cut is not None:
+        center_x = BOARD_X + cursor_x * CELL + CELL / 2
+        center_y = BOARD_Y + cursor_y * CELL + CELL / 2
+        negative_distance = cut["negative_length"] * CELL
+        positive_distance = cut["positive_length"] * CELL
+        screen.pen = MINT
+        if cut["axis"] == "horizontal":
+            screen.line(
+                center_x - negative_distance,
+                center_y,
+                center_x + positive_distance,
+                center_y,
+            )
+        else:
+            screen.line(
+                center_x,
+                center_y - negative_distance,
+                center_x,
+                center_y + positive_distance,
+            )
+    else:
+        x = BOARD_X + cursor_x * CELL
+        y = BOARD_Y + cursor_y * CELL
+        center_x = x + CELL / 2
+        center_y = y + CELL / 2
+        screen.pen = GOLD
+        screen.shape(shape.rectangle(x + 1, y + 1, CELL - 2, CELL - 2))
+        screen.pen = FIELD
+        screen.shape(shape.rectangle(x + 3, y + 3, CELL - 6, CELL - 6))
+        screen.pen = MINT
+        if cut_axis == "horizontal":
+            screen.line(center_x - 10, center_y, center_x - 4, center_y)
+            screen.line(center_x + 4, center_y, center_x + 10, center_y)
+        else:
+            screen.line(center_x, center_y - 10, center_x, center_y - 4)
+            screen.line(center_x, center_y + 4, center_x, center_y + 10)
+        screen.pen = GOLD
+        screen.shape(shape.rectangle(center_x - 3, center_y - 3, 6, 6))
+        screen.pen = FIELD
+        screen.shape(shape.rectangle(center_x - 1, center_y - 1, 2, 2))
+
+    for index, mona in enumerate(monas):
+        frame = int(badge.ticks / 115 + index * 2) % 7
+        sprites = mona_left_sprites if mona["vx"] < 0 else mona_sprites
+        sprite = sprites.sprite(frame, 0)
+        screen.blit(sprite, vec2(mona["x"] - SPRITE_HALF, mona["y"] - SPRITE_HALF))
+
+
+def draw_hud():
+    screen.pen = WHITE
+    screen.text("MONA SLICE", 16, 8)
+    screen.pen = MINT
+    screen.text("LV %d  %d%%/%d%%" % (level, percent, GOAL), 166, 8)
+    screen.pen = PINK
+    screen.text("PAWS %d" % lives, 272, 8)
+
+    screen.pen = PANEL
+    screen.shape(shape.rounded_rectangle(16, 210, 288, 9, 4))
+    if percent:
+        screen.pen = MINT
+        screen.shape(shape.rounded_rectangle(16, 210, max(2, int(288 * percent / 100)), 9, 4))
+    screen.pen = WHITE
+    if cut is None:
+        screen.text("ARROWS MOVE   SELECT CUT   BACK: %s" % cut_axis.upper(), 16, 224)
+    else:
+        screen.text("MONA IS ON THE MOVE!", 16, 224)
+
+
+def draw_title():
+    screen.pen = INK
+    screen.shape(shape.rectangle(0, 0, screen.width, screen.height))
+    screen.pen = LAVENDER
+    screen.shape(shape.circle(160, 74, 40))
+    frame = int(badge.ticks / 115) % 7
+    screen.blit(mona_sprites.sprite(frame, 0), vec2(148, 62))
+    centered_text("MONA SLICE", 19, WHITE)
+    centered_text("Snip the space. Keep Mona safe!", 122, MINT)
+    centered_text("Carve off empty corners to claim them.", 146, WHITE)
+    centered_text("Reach 75% before your paws run out.", 164, WHITE)
+    if int(badge.ticks / 500) % 2:
+        centered_text("PRESS SELECT TO PLAY", 194, GOLD)
+
+
+def centered_text(text, y, pen):
+    width, _ = screen.measure_text(text)
+    screen.pen = pen
+    screen.text(text, (screen.width - width) / 2, y)
+
+
+def draw_end():
+    screen.pen = INK
+    screen.shape(shape.rectangle(0, 0, screen.width, screen.height))
+    cleared = state == "level_clear"
+    centered_text("LEVEL CLEARED!" if cleared else "OH NO, MONA!", 64, MINT if cleared else PINK)
+    centered_text("Level %d   Territory: %d%%" % (level, percent), 105, WHITE)
+    centered_text("Monas: %d   Best level: %d" % (len(monas), best["level"]), 128, WHITE)
+    if int(badge.ticks / 500) % 2:
+        prompt = "SELECT: NEXT LEVEL" if cleared else "SELECT: TRY AGAIN"
+        centered_text(prompt, 171, GOLD)
+
+
+def update():
+    global cut_axis
+
+    dt = min(0.05, max(0, badge.ticks_delta / 1000))
+    if state == "title":
+        draw_title()
+        if badge.pressed(BUTTON_SELECT):
+            new_game()
+        return
+
+    if state == "playing":
+        if cut is None:
+            move_cursor()
+            if badge.pressed(BUTTON_BACK):
+                cut_axis = "vertical" if cut_axis == "horizontal" else "horizontal"
+            if badge.pressed(BUTTON_SELECT):
+                start_cut()
+        for mona in monas:
+            update_ball(mona, dt)
+        if cut is not None:
+            update_cut(dt)
+        draw_board()
+        draw_hud()
+        return
+
+    draw_end()
+    if badge.pressed(BUTTON_SELECT) and state == "level_clear":
+        start_level(level + 1)
+    elif badge.pressed(BUTTON_SELECT):
+        new_game()
+
+
+run(update)
diff --git a/badge/apps/mona_slice/assets/mona.png b/badge/apps/mona_slice/assets/mona.png
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diff --git a/badge/apps/mona_slice/assets/mona_left.png b/badge/apps/mona_slice/assets/mona_left.png
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index 00000000..1b97c160
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diff --git a/badge/apps/mona_slice/icon.png b/badge/apps/mona_slice/icon.png
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