Oni has a good combat system, truth be told, but the level design is subpar and even the enemy design isn't that good. It tries tho, it's kind of a weirdo version of a fighting scroller (a genre that died a few years before Oni).
Oh yeah i agree with that, the levels are essentially a series of big rooms to fight in with some locked doors that you need to unlock and a secret item stashed in a corner here and there but they are done in the simplest way possible.
It's something one of the developers said, that their target platform at the time was the iMac G3, which mostly only came with an 8MB ATI Rage 128. And I don't think you can rely on the people who would upgrade to sell your game to the people who wouldn't.
That'd be for the low end requirements, similarly to how any PC title of the time would need to work more than on the most high end PCs. In fact, out of the box the many iMac G3s had RAM below the game's minimum requirements (which would need an upgrade) and for some the CPU wasn't even fast enough.
But as i wrote, there weren't any Mac-specific limitations, the Macs of the time were pretty much as powerful as the PCs of the time. It wouldn't be any different from a game developer targeting old PC specs so your "Macintosh game made within Macintosh limitations" is wrong. There were no Macintosh limitations aside perhaps from using OpenGL instead of Direct3D but OpenGL was also on PC and as i wrote at the time it was at its peak in terms of both performance and features.
It was always talked about as being based on pre-existing research, no one said anything about psychologists literally programming the animation themselves. But the claim of Oni being ‘designed by pro architects’ doesn't make any sense if that isn't literally the case.
I explicitly remember reading in interviews (that was 2003 at most, before the game was released) that Valve hired psychologists so they get the game's NPC interactivity right. It was something that i also remember being referenced at some point in a YouTube video as a joke. That was years ago though, so unless i go sleuthing to find the source of that (which i'm not feeling like doing as it is pointless), i can't point to anything off the top of my head and a quick Google search has a ton of false positives.
But this is beside the point, my point was that i'd take both of these with a grain of salt since PR -even back in the innocent 90s- tends to overexaggerate things. Being designed by pro architects can mean that they hired some architect to create a few concept art-like pieces for how the buildings would look but the actual design was made by the level designers at Bungie. Or it could mean that one of the level designers also had some architecture knowledge - you may not know it but at the time architecture was sold to level designers as something that was very useful for them to know.
Of course it could also be that they hired an architect to design the levels but i'm pretty much certain that wasn't the case.