>just as smoothly as a faster PC

No. actually smooth, unlike a PC.

One game frame per each frame sent to the screen. Which the PC would only achieve many years later when it got raw power via 3d acceleration.

AIUI the main limitation with early PC graphics was (1) it was a dumb framebuffer and (2) bandwidth from the system to said framebuffer was too low to replace the entire screen in a single frame. This only really got solved comprehensively in the late 1990s or so, hence prior to that timeframe you were always more or less relying on some kind of "trick" to achieve smooth video output.

And Keen 4 was more fun.

Politely disagree.