Senko Rašić

Comparing Claude Opus 5.5 vs Qwen3.8-Flash-Next, running locally, on the same coding task: Sokoban!

In a slightly different setup than usual, I ran Claude Opus 5.5 and Qwen3.8-Flash-Next through the chatbot interface (not a coding agent); Qwen I ran via llama.app (quantized to 4 bits on an AMD Strix Halo machine with 128GB of unified RAM).

The prompt was a one-liner: “Create a simple but beautiful Sokoban game clone in HTML/JS/CSS (all in one file, no frameworks or 3rd-party libraries).“

Opus (high reasoning effort) took ~4 minutes (I don't have a token count because this was from a web chatbot interface). Qwen took ~31 minutes and 64k tokens. 80% of this was for reasoning (at extra-high effort). Qwen thinks a lot more than Opus!

Both are available at my vibecode benchmarks page. Here's also a side-by-side playthrough of both:

I then had GPT-6 Astra compare the quality of the implementations. I chose Astra so as to not have any bias towards a solution (in case models really do prefer their own).

Across 30 different areas/aspects of each solution, Opus scored 77% and Qwen 70% (100% would be a perfect implementation without downsides or bugs).

Astra concluded the code review with: “Claude’s implementation has a modest but meaningful advantage in correctness and maintainability, with simpler state management, stronger movement safeguards, and fewer consequential bugs.“

Note that this test compared the best frontier model for coding against something I ran completely locally, on a machine sitting next to me. As I wrote earlier this year, open-weights models have become good enough, but it's hard (and expensive) to run a very capable model locally.

For this test I chose Sokoban because, frankly, my usual “frontier” tests, RTS/Warcraft, Minecraft and a flying simulator, were beyond Qwen's reach for a zero-shot. When trying to build an RTS, the model took hours and produced an unusable mess.

The hardware cost for this setup can vary between $3.5k and $6k, depending on luck, availability, and other system components. Not cheap, but not beyond the budget for a small business or affluent techies.

The same amount of money does buy you a few years of Claude Max subscription—purely on that level, it's not easy to justify.

But while I will not be canceling my Claude subscription any time soon, I'd say that for smaller tasks and with more guided steering, this is a usable alternative for those who would prefer to—or must—use local models.