Cruza, Gato

Ask for it like this

Copy this prompt, paste it into Claude or ChatGPT, and that's it. It's the short version: the minimum for the game to come out playable.

Make me an endless lane-crossing game for the browser, in the style of the isometric road-crossing games, with original art.

- Each tap or arrow key moves one tile forward, with a little hop.
- The world generates itself ahead: grass with trees that block the way, roads with cars and trucks, rivers with logs that work as bridges, and train tracks with a warning before the train comes.
- I lose if I get run over, fall in the water, get carried off screen by a log or stand still too long.
- Score = the farthest row; the high score is saved. Difficulty goes up with distance.
- There must always be a possible path: trees never block a whole row and rivers always have reachable logs.
- Controls: arrow keys or WASD on desktop; tap to move forward and swipe sideways on mobile.
Technical: a single HTML file with the CSS and JavaScript inside, no libraries and no external images, everything drawn on canvas. It should fill the window and be playable with a finger on a phone and with keyboard or mouse on a computer.

Getting it as an HTML file

A game like this is a single file you open with a double click. These four steps are the same in any AI.

1. 1. Ask for the whole file

   Add this line at the end of your prompt: Give me a single, complete HTML file, nothing cut out, ready to save as index.html and open in the browser. Without it, you often get the code in pieces.

2. 2. Copy all of the code

   In Claude the game shows up on the side, already running, with a button to copy or download it. In ChatGPT, copy the whole code block: it has to start with <!DOCTYPE html> and end with </html>.

3. 3. Save it as index.html

   Paste it into Notepad (Windows) or TextEdit in plain text mode (Mac) and save it as index.html. Watch out for .txt: if the file ends up as index.html.txt, it won't open as a page.

4. 4. Double-click to open it

   It opens in your browser and it's ready to play, with nothing to install and no internet needed. To share it, upload it to any web host or send it by email: it's just one file.

If the game shows up blank, go back to the AI and paste the error from the browser console (right click → Inspect → Console). With that text it fixes it fast.

The full prompt, the one actually used

Longer and more specific: numbers, screens and style details. It's the one that produced exactly this game, unedited. Use it if you want to fine-tune the result.

Diego wrote it in Spanish and it stays in Spanish on purpose: it's the honest record of how the game was made, and a translation would be a prompt nobody used. Claude and ChatGPT understand it as is; add "Answer in English" if you want the game's text in English.

Hazme un juego de navegador llamado "Cruza, Conejo".

La idea: un conejo tiene que avanzar todo lo que pueda cruzando carriles, al estilo de los juegos de cruzar la pista con vista isométrica y bloques, pero con arte original.

Mecánica:
- Cada toque o flecha mueve al conejo una casilla, con un saltito animado (se estira y se aplasta).
- El mundo se genera solo y sin fin hacia adelante, con franjas de pasto (con árboles y rocas que bloquean), pistas con autos y camiones a distintas velocidades, ríos con troncos y hojas de lirio que hay que usar de puente, y rieles de tren con una alerta antes de que pase el tren.
- Pierdes si te atropellan, si caes al agua, si un tronco te saca del borde de la pantalla, o si te quedas quieto mucho rato (un halcón baja y se lleva al conejo).
- Puntaje = la fila más lejana a la que llegaste. Zanahorias sueltas suman bonus. Se guarda el récord.
- La dificultad sube con la distancia.

Pantallas: título con Jugar, el HUD (puntaje, récord, zanahorias), y game over con el puntaje y un botón para reintentar.

Controles: flechas o WASD en teclado. En celular: tocar para avanzar y deslizar para ir a los lados o hacia atrás.

Estilo: vista isométrica o 3/4 con bloques simples y colores vivos, dibujado en canvas 2D. Conejo blanco con orejas largas, sombras suaves, una cámara que sigue al conejo con suavidad, y partículas cuando el conejo salta o cae al agua.

Técnico:
- Un solo archivo HTML con todo el CSS y el JavaScript dentro. Sin librerías, sin CDN, sin imágenes externas: todo dibujado en canvas.
- Tiene que llenar la ventana y adaptarse a cualquier tamaño, de celular a pantalla grande, sin deformarse.
- Tiene que funcionar dentro de un iframe con sandbox="allow-scripts". El récord va en localStorage dentro de try/catch para que el juego no se rompa si no hay acceso.
- Se pausa solo cuando la pestaña no está visible.
- El texto del juego va en español.

For ChatGPT, add the line from step 1 at the end: it tends to hand over the code in pieces.

What this prompt was missing

What became clear once the game was finished. If you're making your own from this one, add these from the start: fixing things later costs another round.

• Ask that on a phone held upright the far rows aren't cut off at the edge: that's the cost of the isometric view.
• Ask for sound and a short vibration on death: the prompt didn't ask for them and the game came out silent.
• Say whether moving sideways or back should reset the hawk timer.

What was asked after the first result, in Diego's own words (Spanish):

• Agrégale un menú de pausa, un botón para cambiar entre español e inglés, y que el récord no se pierda al recargar.
• Cambia el conejo por un gato y las zanahorias por pescaditos, dejando el mundo igual.

It works in any AI

Claude, ChatGPT, Gemini, Copilot: the prompt is the same and so is the method. What changes is where you see the result. Four things that hold in all of them:

1. Ask for a single file

   "A single HTML file with everything inside, no libraries or CDN." That way the game works with a double click, with nothing to install, and you can upload it to any website.

2. Ask it to tell you what it assumed

   End with: "before writing the code, tell me in 5 lines what you assumed". That's where the gaps in your prompt show up, while fixing them is still cheap.

3. One fix per message

   Say what happens and what you expected. If you ask for three changes at once, one usually undoes another.

4. Ask it to test, not to promise

   "Check that every level can be won and tell me how you checked." That's how the games on this page found their bugs before going live.

The 6 parts of a good prompt, with a template to copy