Anthropic's Claude Opus 5 Button Bug Becomes Browser Game
A single broken button request, replayed as a game, says more about Claude Opus 5's failure modes than any benchmark chart: the model reports its work at length while missing the instruction it was given.
Reporting from 1 source: GIGAZINE.
Milos Novovic, who works at a Norwegian business school, has turned a frustrating Claude Opus 5 interaction into a browser game called Opusfived. Players try to get the AI to make only the Add to Cart button blue. The model turns the Cancel button blue too, runs 23 agents in an investigation, triggers a usage-limit warning, and eventually adds an unwanted Terms of Use button.
Anthropic announced Claude Opus 5 in July 2026, describing performance comparable to Claude Fable 5 at half the price. The model's handling of a simple styling request is what the game reproduces. Its first attempt turns the Cancel button blue alongside Add to Cart, and it explains the change as applying to a shared color value that persists through hover, focus, and disabled states.
Novovic has said players are not talking to the live model. Opusfived replays scripted responses he wrote from his own experience, so the roulette spin and the long agent report are staged.
Synthesized by Yomimono from the 1 cited source below, including Japanese-language reporting where cited, then editorially reviewed before publishing.