10.5 was Leopard actually, 10.4 was Tiger. And both were PPC and thus would require emulation not just virtualization. For something that ran on those what you'd actually probably want to run would be 10.6, because that would give you an Intel based OS that still included Rosetta for PPC compatibility. I can't think of any applications that ran on 10.5 but wouldn't work under Rosetta off the top of my head, though perhaps there were a few. And I vaguely recall there was a security update in 2012 (about 3 years after 10.6 launch) that caused issues with Rosetta, but in a VM you could just not apply it since a VM that old should be isolated anyway, or maybe they later fixed it.
But at any rate I'd assumed that for someone who had "nostalgia" for old games would therefore have played those old games and thus had that system, and thus could just have kept it around as a disk image. I have Mac OS disk images going back to the beginning, it was by far the best way to install anyway because it was so much faster than actually going off the disc (the ease and customizability of network installs was also wonderful, I miss that). For really old stuff you can just emulate it via something like SheepShaver, no need for VM at all. I actually find that's the same as Windows, for all its vaunted backwards compatibility I had the damndest time getting some old games working under W7 even and it was much, much easier to just keep some VMs around cover 98, 2000, and XP. Those are old enough there is full virtual 3D support, even without hardware passthrough.
If you really wanted an old copy of 10.5 or 10.4 or whatever directly despite having not used/kept them, and you didn't want to get it off the net, you could just ask around a Mac site or buy a DVD. A quick look on Ebay shows tons for sale for $10-20, it's not as if they are some rare collector's item. And if you went on some Mac forum and just asked there'd be people with images like me or old discs just sitting around in closets collecting dust you could have for a stamp. It'd be a one-time issue, because then you'd immediate image it and keep it forever since they aren't big (looks like my Mac OS X Server 10.6.dmg is about 6.95GB).
Right you are! I wonder why 10.6 stuck in my head, I even got the first Xeon MP (as a free replacement from Apple for my G5 PowerMac liquid cooling blowing out and destroying my system utterly) in 2006 and it was Tiger. What a time since then. I guess 10.6 Server was the first officially virtualizable version so maybe that's why, but yes you're absolutely right, 10.4(.4) and 10.5 should both be runnable in a modified VM in principle.
But at any rate I'd assumed that for someone who had "nostalgia" for old games would therefore have played those old games and thus had that system, and thus could just have kept it around as a disk image. I have Mac OS disk images going back to the beginning, it was by far the best way to install anyway because it was so much faster than actually going off the disc (the ease and customizability of network installs was also wonderful, I miss that). For really old stuff you can just emulate it via something like SheepShaver, no need for VM at all. I actually find that's the same as Windows, for all its vaunted backwards compatibility I had the damndest time getting some old games working under W7 even and it was much, much easier to just keep some VMs around cover 98, 2000, and XP. Those are old enough there is full virtual 3D support, even without hardware passthrough.
If you really wanted an old copy of 10.5 or 10.4 or whatever directly despite having not used/kept them, and you didn't want to get it off the net, you could just ask around a Mac site or buy a DVD. A quick look on Ebay shows tons for sale for $10-20, it's not as if they are some rare collector's item. And if you went on some Mac forum and just asked there'd be people with images like me or old discs just sitting around in closets collecting dust you could have for a stamp. It'd be a one-time issue, because then you'd immediate image it and keep it forever since they aren't big (looks like my Mac OS X Server 10.6.dmg is about 6.95GB).