DD & Ji Ji: Unity engine ?
No. Some custom engine, all the graphics are in .obj/.mtl/.png format, which is a really weird and inefficient choice, though I guess you could easily mod stuff by loading it into Blender or whatever. I played the demo using Wine and a years-old Vega card, fps stayed locked at 60, so no issues there.
However for me the mouse control had some unpleasant acceleration curve, and there are zero game options of any kind whatsoever, other than remapping keyboard controls. (Which isn't even accurate...it says inventory is I by default, but it's actually tab, and remapping it doesn't do anything.)
The two-weapons thing is neat, but makes weapon switching a bit of a pain. The enemies I encountered that had weapons were all hitscan, and kinda bullet-spongy...that coupled with the weird and unchangeable mouse control made it not very fun to play, so I quit after 15 minutes or so. And yeah, the mix of 8GB, 64-bit only, but DX8 32MB GPU??? is bizarre.
Overall I'm going to say "pass," and go back to waiting for Prodeus to be done. (Now that one is actually a Unity engine game, but has a far lower RAM requirement, way better but still old-school graphics, and no complaints about performance that I've seen. Not to mention a native Mac version.)