Someone on reddit built a very clean replica, and posted a mediocre "digital rain" effect from The Matrix. I started a quick little effort to improve it and that got wildly out of hand. After a week, the resulting discussion of speed limitations concluded that the Apple I can print exactly one letter per frame. It is physically incapable of more. There is only one control character: the newline / carriage-return. Even a simple game at interactive speeds would be impossible. Right? Well. You can probably guess how my brain responds to the word "impossible."
I don't know how directly compatible the Apple II's ROM is. But where "20 EF FF" appears, the game expects to print the contents of the A register and then wait one frame. So insert... it feels wrong to call anything on 1970s hardware a polyfill. But point those JSRs elsewhere as-needed.
If it just prints characters as fast the Apple II is able, don't blink.