diff --git a/data/scenarios/Challenges/00-ORDER.txt b/data/scenarios/Challenges/00-ORDER.txt
index c538cb710..9833e50a1 100644
--- a/data/scenarios/Challenges/00-ORDER.txt
+++ b/data/scenarios/Challenges/00-ORDER.txt
@@ -7,6 +7,7 @@ teleport.yaml
 word-search.yaml
 gopher.yaml
 ice-cream.yaml
+combo-lock.yaml
 hanoi.yaml
 hackman.yaml
 lights-out.yaml
diff --git a/data/scenarios/Challenges/_combo-lock/setup.sw b/data/scenarios/Challenges/_combo-lock/setup.sw
new file mode 100644
index 000000000..7a1bd6756
--- /dev/null
+++ b/data/scenarios/Challenges/_combo-lock/setup.sw
@@ -0,0 +1,85 @@
+def elif = \t. \then. \else. {if t then else} end
+def else = \t. t end
+def doN = \n. \f. if (n > 0) {f; doN (n - 1) f} {}; end;
+
+def colorFromIndex = \i.
+    if (i == 0) {"R"}
+    $ elif (i == 1) {"G"}
+    $ else {"B"};
+    end;
+
+def pixelFromColor = \c.
+    "dial (" ++ c ++ ")";
+    end;
+
+def checkCombo = \noMismatchYet. \stepsTaken. \colorString.
+
+    let remainingCount = chars colorString in
+    if (remainingCount > 0) {
+
+        let splitted = split 1 colorString in
+        let nextLetter = fst splitted in
+        let remainingLetters = snd splitted in
+        let expectedPixel = pixelFromColor nextLetter in
+
+        move;
+        isExpectedHere <- ishere expectedPixel;
+        checkCombo (isExpectedHere && noMismatchYet) (stepsTaken + 1) remainingLetters;
+    } {
+        turn back;
+
+        // Replace the cell watches
+        doN stepsTaken (watch down; move);
+        turn back;
+        return noMismatchYet;
+    };
+    end;
+
+def unlockGate = \n.
+    move;
+    turn right;
+    move;
+    turn left;
+    doN n (grab; move);
+    return ()
+    end;
+
+def doUntilCorrect = \colorString.
+    isCorrect <- checkCombo true 0 colorString;
+    if isCorrect {
+        let remainingCount = chars colorString in
+        unlockGate remainingCount;
+        return true;
+    } {
+        wait 1000;
+        doUntilCorrect colorString;
+    };
+    end;
+    
+def createCombo = \colorString.
+    // Scenario map starts with red pixels to
+    // mark the combo sequence
+    redPixelHere <- ishere $ pixelFromColor "R";
+
+    if redPixelHere {
+        r <- random 3;
+        let newColor = colorFromIndex r in
+        watch down;
+        move;
+        createCombo $ newColor ++ colorString;
+    } {
+        turn back;
+        return colorString;
+    };
+    end;
+
+def go =
+    comboString <- instant (      
+        move;
+        createCombo "";
+    );
+    // say comboString;
+    instant $ doUntilCorrect comboString;
+    end;
+
+go;
diff --git a/data/scenarios/Challenges/_combo-lock/solution.sw b/data/scenarios/Challenges/_combo-lock/solution.sw
new file mode 100644
index 000000000..a51af436a
--- /dev/null
+++ b/data/scenarios/Challenges/_combo-lock/solution.sw
@@ -0,0 +1,65 @@
+def moveToLock =
+    emptyHere <- isempty;
+    if emptyHere {move; moveToLock} {};
+    end;
+
+def cycleCombos = \n.
+    wait 1;
+    entityNorth <- scan north;
+    let hasGate = case entityNorth (\_. false) (\x. x == "gate") in
+    if hasGate {
+        if (n > 0) {
+            drill down;
+            maybeNextEnt <- scan east;
+            case maybeNextEnt return (\_. turn east; move; cycleCombos 3);
+            cycleCombos $ n - 1;
+        } {
+            turn west;
+            move;
+        };
+    } {}
+    end;
+
+def moveUntilBlocked =
+    isblocked <- blocked;
+    if isblocked {} {
+        move;
+        moveUntilBlocked;
+    };
+    end;
+
+def toLeftEdge =
+    turn north;
+    move;
+    turn left;
+    moveUntilBlocked;
+    turn north;
+    end;
+
+def goUp =
+    toLeftEdge;
+    move; move; move;
+    end;
+
+def grabBitcoin =
+    move; move;
+    turn right;
+    move; move;
+    grab;
+    end;
+
+def go =
+    moveToLock;
+    cycleCombos 3;
+    goUp;
+    cycleCombos 3;
+    goUp;
+    cycleCombos 3;
+    goUp;
+    cycleCombos 3;
+
+    toLeftEdge;
+    grabBitcoin;
+    end;
+
+go;
diff --git a/data/scenarios/Challenges/combo-lock.yaml b/data/scenarios/Challenges/combo-lock.yaml
new file mode 100644
index 000000000..b1beec2d0
--- /dev/null
+++ b/data/scenarios/Challenges/combo-lock.yaml
@@ -0,0 +1,135 @@
+version: 1
+name: Combination locks
+author: Karl Ostmo
+description: |
+  Unlock the gates
+creative: false
+seed: 4
+objectives:
+  - goal:
+      - |
+        Several combination-locked gates lie between you
+        and treasure.
+      - |
+        Each "dial" can be one of three colors.
+        `drill` a dial to cycle to its next color.
+        The adjacent `gate`{=entity} opens when the correct
+        combination is set.
+      - |
+        Unlock all of the combination locks and `grab`
+        the `bitcoin`{=entity}.
+    condition: |
+      as base {has "bitcoin"};
+robots:
+  - name: base
+    dir: [1, 0]
+    display:
+      invisible: false
+    devices:
+      - ADT calculator
+      - branch predictor
+      - hourglass
+      - comparator
+      - compass
+      - dictionary
+      - drill
+      - grabber
+      - lambda
+      - lodestone
+      - logger
+      - keyboard
+      - net
+      - scanner
+      - strange loop
+      - treads
+  - name: lockbot
+    system: true
+    dir: [1, 0]
+    display:
+      invisible: true
+    program: |
+      run "scenarios/Challenges/_combo-lock/setup.sw"
+solution: |
+   run "scenarios/Challenges/_combo-lock/solution.sw"
+entities:
+  - name: gate
+    display:
+      char: '#'
+    description:
+      - A locked door
+    properties: [known, unwalkable]
+  - name: "dial (R)"
+    display:
+      char: '•'
+      attr: red
+    description:
+      - A red dial
+    properties: [known]
+  - name: "dial (G)"
+    display:
+      char: '•'
+      attr: green
+    description:
+      - A green dial
+    properties: [known]
+  - name: "dial (B)"
+    display:
+      char: '•'
+      attr: blue
+    description:
+      - A blue dial
+    properties: [known]
+recipes:
+  - in:
+    - [1, "dial (R)"]
+    out:
+    - [1, "dial (G)"]
+    required:
+    - [1, drill]
+    time: 0
+  - in:
+    - [1, "dial (G)"]
+    out:
+    - [1, "dial (B)"]
+    required:
+    - [1, drill]
+    time: 0
+  - in:
+    - [1, "dial (B)"]
+    out:
+    - [1, "dial (R)"]
+    required:
+    - [1, drill]
+    time: 0
+known: [boulder, water, bitcoin]
+world:
+  dsl: |
+    {water}
+  upperleft: [-1, -1]
+  offset: false
+  palette:
+    '.': [grass, erase]
+    '$': [grass, bitcoin]
+    '@': [grass, boulder]
+    '#': [grass, gate]
+    'B': [grass, erase, base]
+    'c': [grass, dial (R)]
+    'a': [grass, erase, lockbot]
+  map: |
+    .......$......
+    @@@@@......@@@
+    ....@######@..
+    ....acccccc...
+    ..............
+    @@@@@.....@@@@
+    ....@#####@...
+    ....accccc....
+    ..............
+    @@@@@....@@@@@
+    ....@####@....
+    ....acccc.....
+    ..............
+    @@@@@...@@@@@@
+    ....@###@.....
+    ..B.accc......
+    ..............
diff --git a/test/integration/Main.hs b/test/integration/Main.hs
index 5993b547a..416cf0294 100644
--- a/test/integration/Main.hs
+++ b/test/integration/Main.hs
@@ -216,6 +216,7 @@ testScenarioSolutions rs ui =
         , testSolution (Sec 3) "Challenges/word-search"
         , testSolution (Sec 10) "Challenges/bridge-building"
         , testSolution (Sec 5) "Challenges/ice-cream"
+        , testSolution (Sec 10) "Challenges/combo-lock"
         , testSolution (Sec 15) "Challenges/wave"
         , testSolution (Sec 3) "Challenges/arbitrage"
         , testSolution (Sec 10) "Challenges/gopher"
@@ -293,7 +294,7 @@ testScenarioSolutions rs ui =
         , testSolution Default "Testing/479-atomic-race"
         , testSolution (Sec 5) "Testing/479-atomic"
         , testSolution Default "Testing/555-teleport-location"
-        , testSolution Default "Testing/562-lodestone"
+        , testSolution (Sec 2) "Testing/562-lodestone"
         , testSolution Default "Testing/378-objectives"
         , testSolution Default "Testing/684-swap"
         , testSolution Default "Testing/699-movement-fail/699-move-blocked"