I’m not sure if it is fair to use such a modern development environment (cc65 C compiler of about 2012-2016), and then to claim it being an “authentic” example to what experience could be had in 1977. That can certainly be debated, but I think it would be more useful to use this point as an example for why software is fundamentally “behind” in the capabilities of the hardware system.
In 1977, the PET itself would have to be used to construct any software for the PET – because there was no other system available. Consider: simple things like “copy and paste” would not be available, no multi-tasking to ALT-TAB over to notes, or a worksheet itemizing ideas, or Googling memory map addresses. And development tools (utility functions) used to help in your development, they would need to be carefully stored on cassette (or printed out and re-typed).
While the built in ROM BASIC offered a great amount of utility, I would argue that the game such as DH could not be written using BASIC. So perhaps this is some sort of “axiom”, that hardware is fundamentally “more bleeding edge” and it takes time for software tools and understanding to grasp that new potential.
As such, when actually running vintage period software from 1977, we cannot be overly critical of that software. The earliest software maybe considered only 8K to be available. I noticed the Commodore BASIC had no RENUMBER feature, so failing to plan ahead could result in some very tedious manual renumber of BASIC program statements.
And these days, Sony or Microsoft may give “early access” to certain key developers, for them get an early chance to learn features and aspects of the new hardware and be better prepared for it in upcoming game releases. This was not the case in 1977, as it was a brand new venture that was keenly aware of imminent competition, nobody fully anticipated what the systems would be used for. Some people may not actually give Wozniak or Peddle that much credit as pioneers, viewing them just as “integrators” that were lucky. While that may be true, but to be fair: these were engineers who worked tirelessly on their craft, sleep-ness nights preparing for demonstrations and conferences, and doing the work to ensure their chips stayed solid enough to function. They dedicated their time and “pushed through” to make their product become a reality, and it is important to recognize that kind of drive.