GPT 5.6 Sol vs. Fable 5, Head to Head: Fable Edges Out a Bike Game Build at 3x the Cost

After noting that GPT 5.6's benchmarks claim to beat Opus and Fable at a fraction of the cost, the creator says quoting numbers alone is boring -- he spent a full day running both models on real work instead. The setup: Claude (running Fable 5) on the left, Codex (running GPT 5.6 Sol) on the right, both fed identical prompts to compare behavior directly.

The first test: 'build a genuinely fun, playable open-world bike game that runs in the browser.' Fable 5 finished in 21:37 for $14.22; GPT 5.6 Sol finished in 23:00 for $4.50. Time was close, but output tokens told a different story -- roughly 90,000 for Fable versus 31,000 for Sol, nearly a 3x gap.

Playing both builds, the creator judged Fable's version to feel more like a genuine open-world GTA-style experience, with better exploration and physics. He prioritized output quality over cost and called this round a clear win for Fable 5.

Wrapping up, the creator placed GPT-5.5 and Opus roughly on par, with Sol a clear step above both -- but concluded there's still a meaningful gap between Sol and Fable 5. He stressed that benchmarks alone aren't enough; judgment has to come from actually using a model on day-to-day work, and results will vary by use case, harness, and skill setup.