If you experience a "Fatal Error" regarding memory on modern systems (especially those with more than 4GB of RAM), you may need to use a "Large Address Aware" (LAA) patch or adjust your boot settings to limit recognized RAM. The GOG version typically handles these fixes automatically.
Since this is a classic title from the mid-2000s, the most reliable way to get it running on modern PCs is through digital storefronts that provide patched versions:
Offers both the original Direct Action and the High Treason expansion. It’s the easiest way to keep the game in your digital library.