Space Cat: make a phone game from one prompt

One prompt in Gemini and you have your own phone game. Then find where the AI went wrong, fix it, and make the game yours.

What you’ll get

A game you can play on your phone right away: an astronaut cat catches stars and dodges rocks. Press “Play the example” above. It’s exactly what Gemini made from the prompt below.

Steps

Open gemini.google.com. If you’re under 13, do it together with a parent, on their device.

Copy the whole prompt and send it:

Make a phone game in one HTML file. Don't connect anything from the internet: no Tailwind, no CDN, no fonts, only your own CSS and JavaScript inside the file. At the bottom of the screen is a cat in a space helmet. I move it left and right with my finger (on a computer, with the arrow keys). Yellow stars and purple rocks fall from the top. A star gives 1 point, a rock takes away one of 3 lives. The more points I have, the faster everything falls. Show the points and lives at the top, and at the end a screen "Game over — tap to play again". Blue space with little stars. No images, draw everything on the canvas.

Wait about a minute. The game appears. Press Preview and play.
Find the AI’s mistake (see the question above). In all our tests the background came out almost black. Fix it with one message:
```
The background is almost black, but I asked for a blue space. Make the background bright blue, don't change anything else.
```
Press Download (sometimes it’s in the Export menu). The file opens in any browser.

Make the game yours

Send one change at a time and check the game each time:

Replace the cat with a dragon, and the stars with coins.
Add a heart that sometimes falls and gives back one life.
When I catch 5 stars in a row, give double points and show "COMBO!".

Change the prompt

Before sending, swap a few words to get a different game:

“a cat in a space helmet” → “a penguin”, “stars” → “fish”, “rocks” → “icicles”, “blue space” → “blue sea”
“A star gives 1 point” → “A star gives 5 points”
“one of 3 lives” → “one of 5 lives”, which makes the game easier

Change only the words, and keep the rules about the internet and Canvas.

Want more? The next step is the mission “Space Cat, 3 Levels and a Win”: levels, sounds, hearts, and a trophy.

If it doesn’t work

No “Preview” button? Write: “Show the game in Canvas.”
The AI says it changed everything, but the game is the same? That happens. Write: The game didn't change. Show the updated game in Canvas.
The game won’t start? Tell the AI what you see: “The screen is empty, the cat doesn’t appear.”