GPT-6 Astra Completes Portal Without Human Controls

Sep 8, 2026
OpenAI's GPT-6 Astra completed Valve's Portal in an autonomous experiment that took almost 24 hours and used 3,336 tool calls.
GPT-6 Astra Completes Portal Without Human Controls

An experimenter using OpenAI's GPT-6 Astra completed Valve's Portal without human control, according to Notebookcheck. The model played the full three dimensional game without a walkthrough or scripted assistance.

A local Model Context Protocol server connected the model to a modified version of SourcePauseTool. The system provided screenshots and player coordinates, then executed the model's button inputs. Portal remained frozen while Astra reasoned and resumed for a specified number of game ticks after each decision.

The session lasted 23 hours and 43 minutes, including interruptions and idle periods. Removing the reasoning pauses reduced the recorded gameplay to about two hours. The run required 3,336 tool calls and generated $571.18 in API charges at list prices, though a $200 monthly Codex Pro subscription covered the experiment.

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