It looks like I misremembered a bit. The first iteration that blew up was AI Dungeon 2 (probably this link: https://news.ycombinator.com/item?id=21717022 ), which he apparently had to shut down after a day or two because it ended up costing $20,000 for weird GCS reasons.

It was briefly an easy way to access GPT-3 before the public release, but that was later and apparently not as important as I thought.