Key Takeaways

  • Viral AI video game mashups rack up millions of views, but open-source documentation warns players not to run opening sequences because collision glitches crash the build immediately.
  • John Coogan compares current AI game mods to the viral 2023 Harry Potter Balenciaga video: high meme value that never translated into a feature film.
  • Jordi Hays notes that the broader gaming community will only embrace AI when a beloved franchise releases a game that is noticeably better because of the tech.
  • The barrier keeping AI prototypes from becoming playable software is Cargill's 90/90 Rule of Software Engineering.

The Cargill's 90/90 Rule of Software Engineering

Coined by Tom Cargill at Bell Labs, the rule states:

  • The First 90%: The first 90% of the code accounts for the first 90% of the development time.
  • The Remaining 10%: The remaining 10% accounts for the other 90% of development time.

As Coogan puts it: “You get 90% of the way there you're like great I only have 10% and then you spend even more time on that last 10% no matter how much you estimate it things always grow in scope.”

When This Works (and When It Doesn't)

Cargill's rule applies directly to complex software systems, game physics, and AI wrappers. Generating assets, character skins, or baseline code takes days with modern tooling. Fixing the physics clipping, edge-case memory leaks, and broken save states takes months. The first phase looks like magic on social media. The second phase is grinding engineering work that kills momentum.

“In the developers documentation for like the open-source implementation of this mod, it says like don't start the game normally,” Coogan points out. “Like do not try and play the opening sequence. It will break.”

The rule fails to apply only when your product does not require reliability. If your entire business model is social engagement or temporary hype, 90% completion is enough. “The base game remains dominant in terms of like actual entertainment value,” Coogan says. “This is pure meme value. And so it feels like it's another Harry Potter Balenciaga moment, but for video games.” But if your product requires users to trust it with their workflows, data, or long gaming sessions, the final 10% determines whether you have a company or just a demo.

What to Do With This

If your team just built a flashy internal AI prototype in 48 hours, do not announce a launch date based on that pace. Take your remaining backlog of edge cases, multiply your time estimate by five, and test the fragile seams first.

Walk through your product like a hostile user this week: try the standard onboarding flow from a fresh account, click buttons out of sequence, and run dirty data through the pipeline. If the app crashes when you deviate from the scripted demo path, you are still in the second 90%.