what is the status of Slotmans 'prince of persia' ?

About the underevaluated vdp cmd engine i think good examples of sw sprites are kpiball from matra or blade lords. they use smooth sw sprites
(kpi uses also some big balls)

So even having a z80 access would not improve almost anything (to be precise, in some situation could improve the way we can access vram, resulting in a improvement, but on the majority this is not the true problem) because the video accesses from/to CPU MUST WAIT THE availability of VRAM. Only when VRAM is idle for the task of video generation the CPU can access. And the problem here is that the VRAM is almost always busy for video task.Then I guess the real solution would be to have the VRAM as dual-ported RAM so that the Z80 and the VDP can access VRAM at the same time. ;) Ok, it's probably a tad expensive but hey, we'd at least have a fast machine! :P

Not required. if VRAM can cope with a half period of access then both the vdp / z80 can use it more faster.
That's the secret of advram. Having those vram chips allowed also a faster vdp without the needing to change the way z80 interacts with vram. take in mind that v9990 uses dual port ram but is i/o based like the other vdp's. And it's not slow.... So not a question of way to access, mainly a question of vram speed....

Bu IIRC PoP was never officially released for ZX. There's just a Russian port made for some of these CCCP clones with higher CPU clocks and subtle hardware differences. Again, I might be totally wrong

Ok. Checked! The Speccy-alike version is not that bad. You can all check it here. Please note that "World of Spectrum" is apparently entitled to host these games, therefore linking the playable java version isn't against the MRC policies.

kpiball from matra

Not Matra, but spanish team Boh-Ken ( some of them now in Kraliceck)

Just pointing that out