Evidence - Opus 5.5 today vs launch regression with same prompt (Godot Engine)

A user reported a regression in Opus 5.5 on their Mac, noting that initial tests on launch day passed "with flying colours" but later identical prompts yielded "clearly inferior result[s]". The user, who has a nostalgic connection to the game "Lander" by Elite creator David Braben, emphasized that while LLMs are non-deterministic, the observed differences were too significant to be attributed solely to non-deterministic behavior.

This report provides a direct comparison of Opus 5.5's performance at launch versus its current state, highlighting a regression unlike typical non-deterministic LLM behavior.