I tested GPT-5.2 Codex vs Gemini 3 Pro vs Claude Opus on real dev tasks

Benchmarking Leading AI Coding Models: A Real-World Comparison of GPT-5.2 Codex, Gemini 3 Pro, and Claude Opus

In the rapidly evolving landscape of artificial intelligence, several models have recently emerged as frontrunners in code generation and automation. Among these, GPT-5.2 Codex, Gemini 3 Pro, and Claude Opus have garnered significant attention on platforms like Twitter and industry forums for their impressive capabilities. Given their recent release and comparable benchmark performances, I decided to conduct a practical comparison to evaluate their strengths and weaknesses in real-world development tasks—specifically focusing on non-agentic coding scenarios.

Objective and Approach

Rather than relying solely on standard benchmarks, I selected three representative development tasks that encompass UI design, game logic, and algorithmic problem-solving:

1. Create a simple Minecraft clone using Python and Pygame
2. Reproduce a Figma dashboard (with access to Figma API)
3. Solve a challenging LeetCode problem with a low acceptance rate (10.6%)

This approach aims to assess each model’s ability to handle diverse coding challenges that developers frequently encounter.

Summary of Results

Here’s an overview of how each model performed across the tasks:

| Model | Strengths | Weaknesses |
|————————|——————————————–|———————————————————|
| Gemini 3 Pro | Excels in UI/frontend tasks; created a polished 3D Minecraft clone; best at replicating Figma layouts | Struggles with complex algorithmic problems (failed early on LeetCode TLEs) |
| GPT-5.2 Codex | Consistent across tasks; built a functional Pygame Minecraft; correct LeetCode solution (but times out on large cases) | Slightly less polished UI; suboptimal performance on larger algorithmic inputs |
| Claude Opus | Mediocre performance overall; somewhat disorganized code for UI projects; TLEs on LeetCode | Poor UI results; failed to complete the Minecraft clone effectively |

Task-Specific Observations

1. Python Pygame Minecraft Clone

• Gemini 3 Pro delivered the most impressive prototype, including 3D rendering, smooth movement, and a playable mini-game.
• GPT-5.2 Codex produced a functional version with multiple block types and basic FPS mechanics.
• **Claude Op