I’ve dreamed of this silly game for years, and only Gemini 3 could bring it partially to life.
Google unveiled its powerful new Gemini 3 models this week, and I decided to take Gemini 3 Pro for a test drive on one of my pet projects: Thumb Wars, a digital version of the classic hand-to-hand game I used to play with my kids. You know the one, where you grasp each other’s hands and then use just your thumbs to battle it out or “wrestle”. To win, you simply have to “pin” the opponent’s thumb under your own.
TechRadar AI Week 2025
This article is part of TechRadar’s AI Week 2025. Covering the basics of artificial intelligence, we’ll show you how to get the most from the likes of ChatGPT, Gemini, or Claude, alongside in-depth features, news, and the main talking points in the world of AI.
This is not the first time I’ve used generative AI to help me create a digital game. I’ve previously coded a massive Tic-Tac-Toe-style game with ChatGPT and, more recently, recreated the Asteroids arcade game using Claude’s artifacts.
Claude, in particular, impressed me with its prompt-driven coding skills, what many are now calling “Vibe Coding,” where instead of writing code, you just tell the AI what you want – vibing with the AI results – nudging it along with subsequent prompts to get the final code you want.
For my latest gaming project, I started with Gemini 3 Pro but also fed the same prompt to ChatGPT 5.1 and Claude Sonet 4.5. The results are all quite different, and only one delivered a game I might play again and again.
I started in Google’s AI Studio, where I accessed the Gemini 3 Pro Preview (access to the Pro version usually costs $19.99 a month, though you can get a free 3-month trial).
My prompt, which you’ll see below, didn’t include a tremendous amount of detail, but I assumed I could check out the result and then offer additional prompts to adjust and improve the game.
Prompt:
I have an idea for an app. I want it to feature two virtual thumbs that engage in a thumb war and call it Thumb Wars. Users select their thumb (including preferred skin color), and then outfit them Lucha Libre-style. They then wait for another player (anywhere in the world) to join and accept their challenge. The play area resembles a wrestling ring. The thumb action is controlled by tapping the screen with one or two fingers. One finger is a straight attach. Two fingers is a sweep move to knock the other thumb over. Three falls of your opponent and you win.
Can we build this as a Web-based app and show me a demo?
To be honest, I thought Gemini 3 Pro might fail. Even though I could see my dream Thumb Wars game in my head, I worried that Gemini would quickly spot the logic gaps and tell me to “try again.”
Instead, Gemini 3 Pro was fully onboard: “Yes, this is absolutely buildable as a Web-based app (PWA). In fact, a web app is a great choice for this because players can join instantly via a link without downloading a 200MB app store binary.”
It followed with a breakdown of all the ways it could build the game’s front and back ends, and even how it could create a “Lobby” for multi-player matchmaking.
Gemini couldn’t create a backend host but quickly pivoted to building a usable “single-screen simulation”.
The HTML code, which appeared within seconds, was surprisingly tight. I copied it and then put it in an unformatted text file with an “HTML” extension. Then I opened it in Chrome. Here’s what I saw:
Image 1 of 2
It was, in some ways, impressive. The game worked, and Gemini’s own decision-making skills were evident throughout. Some choices, like a ring that looks like a strip of caution tape, are not great. But Gemini 3 Pro got the thumb shape more or less right, and it smartly decided to generate a robot opponent since this version of Thumb Wars was not yet online. It also smartly filled in a gap in my game development strategy.
Even though I defined gameplay as controlled by screen taps, Gemini 3 Pro knew I needed another control strategy for a web-based game played on a desktop or laptop. So, it gave me keyboard control options for jabs and sweeps.
I loved how it let me completely customize the colors for skin and the mask.
Still, I knew we could do better. I followed with this prompt:
This is fantastic. I still want to at least offer different mask options.
Also:
Make the ring look a bit more realistic (it should have four sides)
Make the thumbs look just a little more like thumbs
Let’s start with the thumbs further apart and maybe add the ability to move foward and back with the keyboard arrow keys
Make the attacks a bit more dramatic
Gemini 3 Pro generated a Version 2.0 with, among other updates, “CSS Perspective to tilt the [ring] floor,” and drama in the form of “the whole camera shakes when a heavy hit lands.”
The result was a significantly longer HTML file and guidance on how to test the new file, including “The Setup: Notice the new menu. Pick “Shadow Assassin” or “The Peacock” to see the CSS shape changes on the mask,” and “The Visuals: The thumbs now look more organic (rounded edges, distinct nail) and the ring has depth (ropes in the foreground/background).”
Here’s what the file looked like when I opened it in Chrome:
Image 1 of 2
This was quite a leap. I got my ring and some dimension, but I soon realized that I’d only managed to create a one-dimensional game on a 3D plane. I also noticed that the thumbs could start outside the ring and leave it during a match.
I fed Gemini 3 Pro this prompt, but it’s also worth noting that at no point does Gemini 3 Pro ask me to start over or remind it of what we did before.
Looking good. A few more small updates
The thumbs should start the battle inside the ring
Allow the thumbs to move up and down in the ring with the up and down arrow keys
The movement on the vertical axis in a 3D environment presented a host of challenges that, to my surprise, Gemini quickly sorted and planned for. Before its new HTML code, it explained its strategy:
“Depth & Perspective:
As you walk “Up” (away from camera), the thumb gets smaller and darker.
As you walk “Down” (closer to camera), the thumb gets larger.
This creates a realistic 3D effect inside the CSS environment.
Z-Axis Hit Detection: You can no longer punch someone if they are on the other side of the ring vertically. You must line up your shadow with theirs to land a hit.
Foreground/Background Ropes: The ring is now split into layers. The bottom rope is in front of the thumbs, so if you walk close to the camera, you are visually “inside” the ring behind the ropes.”
The HTML file produced this result:
Image 1 of 2
The control and motion across the 3D ring are impressive. I was disappointed, though, that we lost the configuration options. I went back and asked Gemini to add those back in. As Gemini accurately assessed before building its biggest HTML file yet, “This combines everything we have built so far.”
My game won’t win any awards, but the result was, considering what we started with, near perfect.
Image 1 of 2
ChatGPTs turn
Next, I took my base prompt to ChatGPT 5.1. Like Gemini 3 Pro, ChatGPT expressed excitement, “Yes, we can absolutely build a web-based demo of Thumb Wars. Here’s a first-playable prototype you can run in your browser,” and quickly got to work.
It took considerably longer for ChatGPT 5.1 to write the HTML/CSS/JavaScript code, and the result was a single configuration and gameplay screen that I initially liked (it gets points for cuteness), but I soon saw its significant limitations.
Unlike Gemini, ChatGPT didn’t bake in desktop controls, which meant I couldn’t use a keyboard or even trackpad taps to control the thumbs. I needed to give ChatGPT more detail if this was going to work.
I delivered this prompt to ChatGPT:
Nice start. Let’s make these adjustments
I need a more realistic-looking ring
After players choose their thumb style, switch to a full-screen ring for match
In lieu of an online opponent, default to playing against the computer
Make the thumbs look a bit more realistic
Allow for keyboard attack control. Arrow keys for movement X and R keys for two kinds of attack
ChatGPT responded, “Love these tweaks – this is starting to feel like an actual little fighting game.”
We’ll see…
Image 1 of 2
ChatGPT 5.1 split the game into a setup and main gameplay screen, but it still lacked the depth and excitement of the Gemini screen. What’s more, even though ChatGPT told me I would be pitted against a CPU opponent, the other thumb barely moved. I just didn’t feel like this game was moving in the right direction. We weren’t vibing.
Claude’s turn
Next, it was Claude Sonet 4.5’s turn. I’d previously had some success with Claude Artifacts, which helped me build that Asteroid game, so I had high hopes for its Thumb Wars attempts.
Clause was no less enthusiastic, telling me, “I love this concept! Let me build a demo of Thumb Wars for you. This will be a fully functional prototype with:
Character customization (thumb selection, skin tone, lucha libre masks/outfits)
A wrestling ring play area
Tap-based combat (1 finger = jab, 2 fingers = sweep)
Three-fall match system
Matchmaking simulation (for the demo, you’ll play against an AI opponent)
Let me create this for you:”
Image 1 of 3
Thanks to Claude’s Artifact capabilities, it immediately presented a functioning game window next to the code.
The customization controls were great, especially the option to choose to play with the right or left thumb. However, the game barely functioned, and mostly because, as I assessed with the other platforms, I didn’t provide enough information, especially for desktop controls.
I tried using a prompt similar to the one I provided to Gemini 3 to help guide Claude toward a better, more functional version of the game. The key update, though, was me asking for it to assign keyboard controls.
I’d show you what it looked like, but the Claude thumb Wars update was virtually unchanged. It didn’t even implement the promised keyboard controls.
In the end, it was barely a contest. Gemini 3 Pro was faster and smarter. In places where I provided skeletal guidance, it filled in the gaps to make my dream game a reality. Gemini 3 Pro seemed to almost intuit my intention and, in general, gave, considering the limitations, the best possible result.
I may return to this vibe-coding task with Gemini 3 Pro, and perhaps someday you, too, will be playing Thumb Wars on the desktop (and later smartphone!).
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lance.ulanoff@futurenet.com (Lance Ulanoff)
