The timing circuit is there, you just can't read the vertical blank info. Games just ignored it or used a timer on the Mockingboard.
It's one of the reasons the Mockingboard was popular with some developers. You could generate timed interrupts equal to one vertical blank.
So skipping over the "just ignore it" option for a moment, i'd like to know which method is going to get the most "hits"; i like rdvblbar because it's simple to implement, but is that going to work on more physical machines now
than going for the Mockingboard timed interrupt approach?
And if i supply some rdvblbar-based code, is there anyone reading to throw it at a real Apple 2+ to see if Apple Win is lying about it working? =-)
I seem to remember reading more about the vertical blank in some developer notes but I haven't the slightest idea where to find them.
I think someone also created a mod to make the signal readable on older machines but I don't know where I saw that either.
i suspect this goes some of the way towards answering the OP's original question; there aren't many games being written because, although there's information out there
, it's spread quite thinly across the internet and bits contradict each other.