For those with the original CD's on hand, here is relatively easy way to get the game working in Windows 10 64 bit: Use Peixoto's Patch. Google the patch name combined with the Vogon's forum, apparently I'm not allowed to post links on this forum...
The patch sets off some antivirus alarms, due to the use of Auto Hotkey. However the 33 page thread on Vogon's alleviated my concerns, and I've installed it, and my laptop didn't explode. Still, not everybody will be comfortable running it.
Dark Earth runs great with this patch, with only some minor issues (screen transition effect not working). There are also some welcome enhancements included in the patch, like the XBR scaler, which improves the presentation.
It's a workable way of playing the game, while we wait for a GoG release.