Probably worth mentioning that writing a big project in Forth is more like creating an OOP framework.(if you are disciplined)

The end result of that is one doesn't write the program in "Forth" per se but in the domain specific language you create for the job. This is how Forth gets more productive than pure assembly language if the team documents things well and follows the prescribed system.

This was the era before optimizing compilers.[1] The overwhelming majority of commercial games were shipping hand-coded assembly still. Forth had the advantage of low overhead, no-worse-than-a-compiler speed, and better-than-assembly productivity. It was a small time window, but a good fit in the moment.

[1] Non-trivial optimizations were just starting to show up on big systems, but Microsoft C in 1985 was still a direct translator.