The week Grok 4.5 debuted, a community build‑off compared it with OpenAI’s GPT‑5.5 and Anthropic’s Claude Opus 4.8 and Claude Fable 5. Four identical prompts asked each model to generate a single‑file HTML app: a 3‑D Rubik’s Cube, a particle gravity sandbox, and a Breakout game. Each model ran once, with no prompt tuning.

For the 3‑D cube, Opus and Fable produced a correctly colored, animating cube on the first try. Grok’s first render was blank; a single retry yielded a clean cube. GPT‑5.5 rendered only a dark face, missing full geometry. In the sandbox arena, all models succeeded, but GPT‑5.5 delivered the most neon‑glow effect, Grok offered tidy orbiting rings, Fable softened glows, and Opus packed the canvas with dense physics.

The breakout tests were a dead heat: all four models delivered playable, score‑tracking games with smooth paddles. Every output passed functional review.

Speed and cost metrics highlighted Grok’s edge. Median latency: Grok 2.8s, first token 0.44s, throughput 110 tok/s, cost 0.002¢. GPT‑5.5 lagged at 2.0s, 1.26s, 53 tok/s, 0.004¢; Opus 2.6s, 1.16s, 47 tok/s, 0.004¢; Fable 6.3s, 3.47s, 28 tok/s, 0.009¢. Grok’s streaming rate and price make it ideal for high‑volume code generation, while Opus and Fable offer higher reliability for stateful tasks, and GPT‑5.5 excels on short, stylistic replies.