So.... is there just not a fix for this?
Virtually every single "game which won't play on modern systems" ultimately comes down to one of two issues...
1) "Copy protection" schemes which are now broken, or assume you're running the original CD on then-contemporary hardware.
2) Microsoft's ever-changing DirectX contents. The vast majority of issues I've had in that regard, until upgrading to Win7, involved "DirectX3" games not running on DirectX9, or the like. Today, it's roughly half-split between "games which need earlier versions of DirectX" or "games which need DirectDraw" (long since removed from DirectX, and implemented as a "hacky emulation in Direct3D"). The solution to MOST of these is to use a Direct3D wrapper, a DirectDraw wrapper, or a combination (often, today, also including a GLide wrapper). That is, something which intercepts the calls to those older APIs, and reinterprets them (in a fast and lightweight fashion) to commands recognized by more current DirectX implementations.
In the case of Dark Reign, it's BOTH. And, unfortunately, they implemented this in a single EXE file (or rather, a single EXE file for each of the two game version... original or expansion). And the "fix" for the "there's no such thing as DirectDraw" issue, which means you get emulation which is prone to pallet corruption (due to only allowing a single pallet on the entire system at a time... while multiple applications use pallets, including, apparently, the icon bar in Windows Explorer, regardless of what your desktop resolution is!)
So, the "kludge" they used to get around this is to hard-shut-down Explorer (meaning, any windows you had open before are lost, your task bar goes away, etc), then "fudge" the "the correct CD is present" response to the popup window (even though the Window itself remains open until you shut down the computer, hidden as it may be!), then run the game (without any graphical fixes, which means it will show up in 16:9 "stretched out" format rather than the design-intent 4:3, unless you're actually running a 4:3 monitor... and who is, these days???)... and THEN (assuming nothing went wrong) it will restart Explorer once the game exits properly (but will still require a log-out/log-in cycle to get your task tray looking as you expect it to, and to restart all your resident applets, and so forth).
This is simply a BAD SOLUTION. I'll work it out sooner or later... likely by getting ahold of a CD ISO file, though, and running with that mounted, rather than by usign GoG's kludged "fix." And with dgVoodoo, I'll see the graphics uncorrupted and unstretched.
But I should not HAVE to do that.
I also should not have HAD to do that to get F-18E Superhornet working, but GoG never did fix that, though I was able to get it 100% running (using a graphics wrapper, as described above).