They're not the hardest problems we have, they are just very nice benchmark tools because by definition they already run on a computer and you can fairly easily interface an AI with them.

There's probably also a distorting factor in that all the AI research into stock market and military applications probably doesn't get published, so it seems like video game AIs are a much larger percentage of research than it actually is.

A video game is a very well-defined problem, and usually comes with simple metrics for success – health, time, or in Factorio’s case, ultimately science per minute (or per minute played, for AIs?). Real world problems are much harder to define, they are embedded in a very complex ecosystem, and it’s not clear at all what to optimize for.

It is "hardest" in a context of the AI actually having a chance.

There's no problem asking AI for the blueprints to a working faster-than-light spaceship, only we already know the AI will fail, and the way it fails provides no useful information.

I'd love to see a Baba is You or Stephen's Sausage Roll llm environment to gauge spatial reasoning. Stephen's Sausage Roll in particular could be very interesting because the mechanics are incredibly simple but challenging.

DeepMind went from playing Pong to protein folding in a short number of years. There are much harder things for AI to do than playing video games. Also see: self driving cars.