All of these followed the model of a relatively small number of smart people bouncing ideas off each other, reviewing them, building on them, and promoting the good ones.
The difference between that and modern R&D is that modern R&D tries to be industrial rather than academic. Academia is trapped in a bullshit job make-work cycle, where quantity gets more rewards than quality and creativity. There isn't room for mavericks like Einstein. Even if they're out there having great ideas, there's no way for them to be discovered and promoted.
Industry focuses more on fill-in developments than game changer mathematical insights, which are the real drivers of scientific progress.
So there's a lot of R&D-like activity in CS, and occasionally something interesting falls out, like LLMs. But fundamental physics has stagnated.
One of the biggest reasons is that the smartest people don't work in research. They work in finance, developing gambling algorithms.
I disagree that the smartest people work in finance. Some very smart people do. From what I've seen, the ones at the very farthest edge of human ability typically aren't motivated by money.
I'm sure you could conjure up any number of ways to do that, but they won't be trivial, and maintaining those tests while you iterate will only slow you down. And what's the point? Even if the unit-move-and-attack test passes, it's not going to tell you if it looks good, or if it's fun.
Ultimately you just have to play the game, constantly, to make sure the interactions are fun and working as you expect.