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2048 · gemma-4-26b-a4b-it

Build a playable 2048 game with arrow-key tile sliding and merging, smooth animations, a score, and win and lose states.

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user

Build a playable 2048 game with arrow-key tile sliding and merging, smooth animations, a score, and win and lose states.

assistant
thinking
The user wants a single-page 2048 game in `index.html`.
It should have:
- Arrow-key tile sliding and merging.
- Smooth animations.
- Score.
- Win and Lose states.
- No external resources (CSS/JS must be inline).

Plan:
1.  Create `index.html`.
2.  Structure:
    - HTML: Container for game, score, message overlay.
    - CSS: Grid layout, tile styling, animations (transitions for movement/merging).
    - JS:
        - Game state (grid, score, game over/win).
        - Initialization.
        - Input handling (keydown).
        - Logic: Move, Merge, Add random tile, Check game over.
        - Rendering: Update DOM based on state. To achieve "smooth animations", I might need to track positions or just use CSS transitions on tile elements.

Actually, to make animations smooth in a grid-based game like 2048, the standard way is:
- Use absolute positioning for tiles.
- When moving, update the `transform: translate(...)` property.
- When merging, one tile "grows" or they both disappear and a new one appears at the target location.

Wait, a simpler way for a single file:
- Use a 4x4 grid.
- Each cell can hold a tile.
- Represent tiles as objects with `value`, `row`, `col`, and `id`.
- When moving, calculate new positions.
- Use CSS transitions for `top` and `left` (or `transform`).

Let's refine the JS implementation.

Grid: 4x4 array.
Tile object: `{ value, x, y, id }`.
`tiles` array: list of all active tiles.

Movement logic:
1. For a direction (Up, Down, Left, Right):
2. Filter out empty tiles? No, just process each row/column.
3. For each row/column:
    - Collect tiles.
    - Merge them according to 2048 rules (one merge per tile per move, prioritize highest/first).
    - Update positions.
4. Check if any move happened. If yes, add new tile and update score.
5. Check for game over.

CSS:
- `.game-container`: relative positioning.
- `.tile`: absolute positioning, transition.
- `.cell`: the background grid.

Let's write the code.
write index.html (17301 bytes)
toolResult

Successfully wrote 17301 bytes to index.html

assistant
thinking
The game is written. I should check if it's working as expected.
Since I can't "play" it in a browser here, I'll rely on my code logic.
Wait, I noticed a small mistake in my logic in `move`:
```javascript
                                // Update the tile in the tiles array
                                const idx = this.tiles.findIndex(t => t.id === targetTile.id);
                                this.tiles[idx] = targetTile;
```
Actually, `targetTile` is already an object in `this.tiles` if it was added via `addRandomTile`.
The way I handle `this.tiles` and `this.grid` might be a bit redundant.
In `move`, I do:
```javascript
                // After processing moves, update the tiles array to reflect grid state
                // We rebuild it to ensure it only contains active tiles.
                this.tiles = [];
                for (let r = 0; r < this.size; r++) {
                    for (let c = 0; c < this.size; c++) {
                        if (this.grid[r][c]) {
                            this.tiles.push(this.grid[r][c]);
                        }
                    }
                }
```
This seems correct.

One potential issue: the `tile-new` and `tile-merged` animations.
In `render()`, I use:
```javascript
                    if (tile.new) el.classList.add('tile-new');
```
But I'm not removing `tile-new` once it's rendered. However, `tile-new` is an animation that runs on element creation. If I reuse an element, I shouldn't re-apply `tile-new` unless it's actually a new tile.
Actually, `tile-new` is added when the element is created.
And when a tile is moved, I update its `transform`.

Wait, I see a potential problem with `tile-new` and `tile-merged` if I'm reusing elements.
When a tile is created, it has `new: true`.
When `render` is called, it might be a new tile or an existing tile.
If it's an existing tile, `el` is found.

Let's refine the `render` method slightly to ensure animations work correctly.
Current `render`:
```javascript
            render() {
                // 1. Remove tiles that are no longer in the grid
                const currentTileIds = new Set(this.tiles.map(t => t.id));
                const domTiles = this.tileContainer.querySelectorAll('.tile');
                domTiles.forEach(el => {
                    if (!currentTileIds.has(parseInt(el.dataset.id))) {
                        el.remove();
                    }
                });

                // 2. Add or Update tiles
                this.tiles.forEach(tile => {
                    let el = this.tileContainer.querySelector(`.tile[data-id="${tile.id}"]`);
                    if (!el) {
                        el = document.createElement('div');
                        el.className = 'tile tile-new'; // Correct: new tile gets new animation
                        el.dataset.id = tile.id;
                        this.tileContainer.appendChild(el);
                    } else {
                        if (tile.merged) {
                            el.classList.add('tile-merged');
                            setTimeout(() => el.classList.remove('tile-merged'), 200);
                        }
                        // If it was a new tile but we are updating it (shouldn't happen in one frame usually)
                        // but let's be safe. Actually, a tile's 'new' status is only true on its first frame.
                    }

                    el.innerText = tile.value;
                    el.className = `tile ${this.getTileClass(tile.value)}`;
                    if (tile.new) el.classList.add('tile-new'); // Wait, this overwrites the class list

                    // ...
                });
            }
```
Wait, `el.className = ...` overwrites everything.
So `el.className = 'tile tile-new'` in the `!el` block is fine, but then `el.className = 'tile ...'` overwrites it immediately.

Let's fix the `render` method to be cleaner.

Also, the movement logic:
The `while(true)` loop for sliding:
```javascript
                        while (true) {
                            let nextR = currR + dr;
                            let nextC = currC + dc;

                            if (nextR < 0 || nextR >= this.size || nextC < 0 || nextC >= this.size) {
                                break;
                            }

                            const targetTile = this.grid[nextR][nextC];

                            if (!targetTile) {
                                // Slide into empty cell
                                this.grid[currR][currC] = null;
                                currR = nextR;
                                currC = nextC;
                                this.grid[currR][currC] = currentTile;
                                currentTile.row = currR;
                                currentTile.col = currC;
                                moved = true;
                            } else if (targetTile.value === currentTile.value && !targetTile.merged) {
                                // Merge
                                this.grid[currR][currC] = null;
                                targetTile.value *= 2;
                                targetTile.merged = true;
                                // ...
                                moved = true;
                                break; 
                            } else {
                                break;
                            }
                        }
```
If `dr` and `dc` are 0, it will loop forever. But `dr` and `dc` are never both 0.

Let's improve the `render` method.

Also, I should check the tile color for `2048`.
`tile-2048` exists.
`tile-super` for > 2048.

One more thing: `tile-new` is an animation. If I use `el.className = ...` I must include `tile-new` if it's a new tile.

Let's rewrite the `render` method and the `move` method slightly to be more robust.

Actually, I can just overwrite the `index.html` with a improved version.

I will also improve the CSS for the tiles to make sure they look good.
The current `tile-new` and `tile-merged` animations use `transform`.
`tile-new` uses `transform: scale(0)` to `scale(1)`.
`tile-merged` uses `scale(1)` to `scale(1.15)` to `scale(1)`.

Wait, `el.style.transform = 'translate(...)'` will overwrite the `transform` from the animation!
Ah! I should use `translate` in the `transform` property and let the animation handle the rest, OR use `top/left` for position and `transform` for animation.
Using `top/left` is often easier for grid games if you want to combine with `transform` animations.
But `top/left` doesn't trigger hardware acceleration as well as `transform`.

Better way:
Positioning: `transform: translate(x, y)`.
Animations: `transform: translate(x, y) scale(1.15)`.
This is tricky because `transform` is one property.

Let's use `top` and `left` for the base position, and `transform` for the scale animation.
`top` and `left` can also be transitioned.

```css
.tile {
    position: absolute;
    width: 80px;
    height: 80px;
    border-radius: 3px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 35px;
    font-weight: bold;
    transition: top 100ms ease-in-out, left 100ms ease-in-out, background-color 100ms ease-in-out;
    z-index: 10;
}
```

And for animations:
```css
@keyframes appear {
    0% { opacity: 0; transform: scale(0); }
    100% { opacity: 1; transform: scale(1); }
}

@keyframes pop {
    0% { transform: scale(1); }
    50% { transform: scale(1.15); }
    100% { transform: scale(1); }
}
```
Then in JS:
`el.style.top = y + 'px';`
`el.style.left = x + 'px';`

And for the merge animation:
`el.classList.add('tile-merged');` where `.tile-merged` has `animation: pop 200ms ease-in-out;`.

This should work well.

Let's fix the `render` and `move` logic in a new `index.html`.
edit {"edits":[{"newText":" <div id=\"game-container\">\n <div class=\"grid\">\n <div class=\"cell\"></div><div
toolResult

Could not find the exact text in index.html. The old text must match exactly including all whitespace and newlines.

assistant
thinking
Ah, I missed some whitespace or something. Let me just rewrite the whole file to be sure and to include the improvements I planned. It's easier than hunting for exact matches for large blocks.

I'll also fix the `tile-new` animation and the `render` method.
The issue with `tile-new` was that I was using `transform` for both position and scale.
I'll switch to `top` and `left` for position and `transform` for animations.
The CSS transition will handle `top` and `left`.

Also, I'll fix the `move` logic slightly to ensure it's solid.

Wait, I'll check the `move` logic again.
When a tile merges, the `targetTile`'s value is updated.
The `targetTile` is already in the grid.
The `currentTile` is removed from the grid.
This seems correct.

Let's rewrite `index.html` completely.
write index.html (15900 bytes)
toolResult

Successfully wrote 15900 bytes to index.html

assistant
thinking
Okay, the code is complete. I've implemented the 2048 game in a single file with the requested features.
- Arrow-key tile sliding and merging.
- Smooth animations (using `top`/`left` transitions and `transform` for pop/appear).
- Score tracking.
- Win (2048) and Lose (no moves left) states.
- No external resources.

The `move` logic is now more robust, rebuilding the `tiles` array from the grid to ensure consistency.
The `render` logic handles adding, updating, and removing tiles in the DOM.
The CSS uses `top` and `left` for positioning to allow smooth movement via transitions, and `transform` for the "appear" and "merge" animations.

Final check of the requirements:
- Single-page web app: Yes.
- All in one file `index.html`: Yes.
- CSS in `<style>`, JS in `<script>`: Yes.
- NO external resources: Yes.
- Playable with arrow-key: Yes.
- Smooth animations: Yes.
- Score, win and lose states: Yes.

I'm ready to finish.

The 2048 game has been built as a single-page web application in `index.html`. It features smooth animations for tile movement, merging, and appearing, along with score tracking and win/lose states. The game is fully self-contained with no external dependencies. To play, simply open `index.html` in any web browser and use your **Arrow Keys** to slide and merge tiles. ```html <!-- index.html --> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>2048 Game</title> <style> :root { --bg-color: #bbada0; --cell-color: #cdc1b4; --text-dark: #776e65; --text-light: #f9f6f2; } body { background-color: #faf8ef; color: var(--text-dark); font-family: "Clear Sans", "Helvetica Neue", Arial, sans-serif; display: flex; flex-direction: column; align-items: center; justify-content: center; height: 100vh; margin: 0; overflow: hidden; } .heading { width: 400px; display: flex; justify-content: space-between; align-items: center; margin-bottom: 10px; } .title { font-size: 60px; font-weight: bold; margin: 0; } .score-container { background: var(--bg-color); padding: 10px 20px; border-radius: 3px; color: white; text-align: center; } .score-label { font-size: 13px; text-transform: uppercase; display: block; } .score-value { font-size: 25px; font-weight: bold; } #game-container { position: relative; width: 400px; height: 400px; background-color: var(--bg-color); border-radius: 6px; padding: 15px; box-sizing: border-box; } .grid { display: grid; grid-template-columns: repeat(4, 1fr); grid-template-rows: repeat(4, 1fr); gap: 15px; width: 100%; height: 100%; } .cell { width: 80px; height: 80px; background-color: var(--cell-color); border-radius: 3px; } .tile { position: absolute; width: 80px; height: 80px; border-radius: 3px; display: flex; justify-content: center; align-items: center; font-size: 35px; font-weight: bold; transition: top 100ms ease-in-out, left 100ms ease-in-out, background-color 100ms ease-in-out; z-index: 10; box-sizing: border-box; } /* Tile Colors */ .tile-2 { background: #eee4da; color: #776e65; } .tile-4 { background: #ede0c8; color: #776e65; } .tile-8 { background: #f2b179; color: #f9f6f2; } .tile-16 { background: #f59563; color: #f9f6f2; } .tile-32 { background: #f67c5f; color: #f9f6f2; } .tile-64 { background: #f65e3b; color: #f9f6f2; } .tile-128 { background: #edcf72; color: #f9f6f2; font-size: 30px; } .tile-256 { background: #edcc61; color: #f9f6f2; font-size: 30px; } .tile-512 { background: #edc850; color: #f9f6f2; font-size: 30px; } .tile-1024 { background: #edc53f; color: #f9f6f2; font-size: 25px; } .tile-2048 { background: #edc22e; color: #f9f6f2; font-size: 25px; } .tile-super { background: #3c3a32; color: #f9f6f2; font-size: 25px; } /* Animations */ @keyframes appear { 0% { opacity: 0; transform: scale(0); } 100% { opacity: 1; transform: scale(1); } } .tile-new { animation: appear 200ms ease-out; } @keyframes pop { 0% { transform: scale(1); } 50% { transform: scale(1.15); } 100% { transform: scale(1); } } .tile-merged { animation: pop 200ms ease-in-out; } #message-container { position: absolute; top: 0; left: 0; width: 100%; height: 100%; background: rgba(238, 228, 218, 0.73); display: none; flex-direction: column; align-items: center; justify-content: center; z-index: 100; border-radius: 6px; } #message-container h2 { font-size: 60px; margin: 0; } .restart-button { margin-top: 20px; padding: 10px 20px; background: #8f7a66; color: white; border: none; border-radius: 3px; font-weight: bold; cursor: pointer; font-size: 18px; } .restart-button:hover { background: #7f6a56; } .controls-hint { margin-top: 20px; color: #776e65; font-size: 14px; } </style> </head> <body> <div class="heading"> <h1 class="title">2048</h1> <div class="score-container"> <span class="score-label">Score</span> <span id="score" class="score-value">0</span> </div> </div> <div id="game-container"> <div class="grid"> <div class="cell"></div><div class="cell"></div><div class="cell"></div><div class="cell"></div> <div class="cell"></div><div class="cell"></div><div class="cell"></div><div class="cell"></div> <div class="cell"></div><div class="cell"></div><div class="cell"></div><div class="cell"></div> <div class="cell"></div><div class="cell"></div><div class="cell"></div><div class="cell"></div> </div> <div id="tile-container"></div> <div id="message-container"> <h2 id="message-text">Game Over!</h2> <button class="restart-button" onclick="game.restart()">Try Again</button> </div> </div> <div class="controls-hint">Use <b>Arrow Keys</b> to move tiles</div> <script> class Game2048 { constructor() { this.size = 4; this.grid = []; this.score = 0; this.tiles = []; this.tileIdCounter = 0; this.gameOver = false; this.gameWon = false; this.tileContainer = document.getElementById('tile-container'); this.scoreElement = document.getElementById('score'); this.messageContainer = document.getElementById('message-container'); this.messageText = document.getElementById('message-text'); this.init(); } init() { this.grid = Array(this.size).fill().map(() => Array(this.size).fill(null)); this.tiles = []; this.score = 0; this.tileIdCounter = 0; this.gameOver = false; this.gameWon = false; this.scoreElement.innerText = '0'; this.messageContainer.style.display = 'none'; this.tileContainer.innerHTML = ''; this.addRandomTile(); this.addRandomTile(); this.render(); } restart() { this.init(); } addRandomTile() { const emptyCells = []; for (let r = 0; r < this.size; r++) { for (let c = 0; c < this.size; c++) { if (!this.grid[r][c]) { emptyCells.push({ r, c }); } } } if (emptyCells.length > 0) { const { r, c } = emptyCells[Math.floor(Math.random() * emptyCells.length)]; const value = Math.random() < 0.9 ? 2 : 4; const tile = { id: this.tileIdCounter++, value: value, row: r, col: c, new: true, merged: false }; this.grid[r][c] = tile; this.tiles.push(tile); } } move(direction) { if (this.gameOver) return; let moved = false; const dr = direction === 'up' ? -1 : direction === 'down' ? 1 : 0; const dc = direction === 'left' ? -1 : direction === 'right' ? 1 : 0; const rowOrder = direction === 'down' ? [3, 2, 1, 0] : [0, 1, 2, 3]; const colOrder = direction === 'right' ? [3, 2, 1, 0] : [0, 1, 2, 3]; this.tiles.forEach(t => { t.merged = false; t.new = false; }); for (let r of rowOrder) { for (let c of colOrder) { let currentTile = this.grid[r][c]; if (!currentTile) continue; let currR = r; let currC = c; while (true) { let nextR = currR + dr; let nextC = currC + dc; if (nextR < 0 || nextR >= this.size || nextC < 0 || nextC >= this.size) { break; } const targetTile = this.grid[nextR][nextC]; if (!targetTile) { this.grid[currR][currC] = null; currR = nextR; currC = nextC; this.grid[currR][currC] = currentTile; currentTile.row = currR; currentTile.col = currC; moved = true; } else if (targetTile.value === currentTile.value && !targetTile.merged) { this.grid[currR][currC] = null; targetTile.value *= 2; targetTile.merged = true; this.score += targetTile.value; this.scoreElement.innerText = this.score; targetTile.row = nextR; targetTile.col = nextC; this.grid[nextR][nextC] = targetTile; moved = true; break; } else { break; } } } } if (moved) { this.addRandomTile(); this.checkGameState(); this.render(); } } checkGameState() { this.tiles = []; for (let r = 0; r < this.size; r++) { for (let c = 0; c < this.size; c++) { if (this.grid[r][c]) { this.tiles.push(this.grid[r][c]); } } } for (let tile of this.tiles) { if (tile.value === 2048 && !this.gameWon) { this.gameWon = true; this.showMessage("You Win!"); } } if (this.tiles.length === this.size * this.size) { let possible = false; for (let r = 0; r < this.size; r++) { for (let c = 0; c < this.size; c++) { const tile = this.grid[r][c]; if (c + 1 < this.size && this.grid[r][c+1] && this.grid[r][c+1].value === tile.value) possible = true; if (r + 1 < this.size && this.grid[r+1][c] && this.grid[r+1][c].value === tile.value) possible = true; } } if (!possible) { this.gameOver = true; this.showMessage("Game Over!"); } } } showMessage(text) { this.messageText.innerText = text; this.messageContainer.style.display = 'flex'; } render() { const currentTileIds = new Set(this.tiles.map(t => t.id)); const domTiles = this.tileContainer.querySelectorAll('.tile'); domTiles.forEach(el => { if (!currentTileIds.has(parseInt(el.dataset.id))) { el.remove(); } }); this.tiles.forEach(tile => { let el = this.tileContainer.querySelector(`.tile[data-id="${tile.id}"]`); if (!el) { el = document.createElement('div'); el.dataset.id = tile.id; this.tileContainer.appendChild(el); } const cellSize = 80; const gap = 15; const x = tile.col * (cellSize + gap) + 15; const y = tile.row * (cellSize + gap) + 15; el.style.left = x + 'px'; el.style.top = y + 'px'; el.innerText = tile.value; el.className = `tile ${this.getTileClass(tile.value)}`; if (tile.new) el.classList.add('tile-new'); if (tile.merged) { el.classList.add('tile-merged'); setTimeout(() => el.classList.remove('tile-merged'), 200); } }); } getTileClass(value) { if (value <= 2) return 'tile-2'; if (value <= 4) return 'tile-4'; if (value <= 8) return 'tile-8'; if (value <= 16) return 'tile-16'; if (value <= 32) return 'tile-32'; if (value <= 64) return 'tile-64'; if (value <= 128) return 'tile-128'; if (value <= 256) return 'tile-256'; if (value <= 512) return 'tile-512'; if (value <= 1024) return 'tile-1024'; if (value <= 2048) return 'tile-2048'; return 'tile-super'; } } const game = new Game2048(); window.addEventListener('keydown', (e) => { switch(e.key) { case 'ArrowUp': game.move('up'); break; case 'ArrowDown': game.move('down'); break; case 'ArrowLeft': game.move('left'); break; case 'ArrowRight': game.move('right'); break; } }); </script> </body> </html> ```

TAKE IT TO CODE

A single self-contained HTML file — copy it and open in any browser, or reuse the prompt with your own pi-agent run.

RUN

modelgemma-4-26b-a4b-it
vendorGoogle
harnesspi-agent
generated2026-07-22

EVALUATION

3/5 partial

2048 board renders and arrow keys slide/merge tiles and update score; WASD, click, drag, wheel, and enter/space do nothing.

Vision grade · anthropic/claude-sonnet-5

MEASUREMENTS

Raw readings from the capture, not a verdict — the grade above is the only judgement. Percentages are how much of the screen changed; the measure under-reports sparse motion on a dark background.

idle motion0.0%
on click0.0%
on drag0.0%
on wheel0.0%
on enter + space0.0%
on arrow keys3.4%
on w/a/s/d0.0%
frame spread23 / 255
console errors0
js errors none

METRICS

runtime243.1s
tokens in12k
tokens out19k
cached18k
cost / run$0.0069