Two players and two graphics cards.
Two players and two graphics cards.
So it makes sense that steam functions this way—it's tied to the service rather than just a system ID. If you're curious about more advanced setups, here are some areas I haven't tested yet: simultaneous HID peripherals (such as Razer, Asus, Corsair mice and keyboards), audio software processing (like Creative Command Center or Sonic Studio), dual support for DirectX and OpenGL, two simultaneous games using both Vulkan and DirectX, two non-Steam titles, plus Sandboxie persistence challenges like saved games and game preferences.
I've experimented with two titles using DX11 and Vulkan settings. Both function properly. I haven't explored OpenGL yet. On the same hardware—same GPU—I ran DX11 and OpenGL games simultaneously, though the OpenGL version crashed into ScummVM. The input devices remain identical (Razer and Logitech), but no extra software is installed. The monitor and both graphics cards are now matching. Previously I had two different cards; switching to a single unit triggered "plug in your SLI connector" alerts, which disappeared after startup. I haven't tested other programs or non-Steam releases from the past two decades, though those would be excellent opportunities for testing!
OpenGL usually handles rendering on multiple systems at once, including several graphics cards. I often purchase two different GPU models for testing purposes—on dedicated desktops it works fine, but with SLI setups it can cause issues.
There’s something I overlooked recently on Windows: the "Windows Sandbox." It could function similarly to sandboxie, though I haven’t used it much myself. If Microsoft has access to their source code, they might have improvements there.
Duplicate Apex is a good idea. Also note the memory requirement: you should have at least as much system RAM as the GPU’s memory plus half of the total memory used by the OS and games. This covers standby program memory, graphics processing, and other inactive components in that area. Edit: October 15, 2021 – Dr_badwolf. Math wording was off.
This setup includes 64GB of memory, yet I was unaware it required additional GPUs.