In the interest of helping anyone that hasn’t picked a method of playing yet, I’ve played through the first 2 missions on the GoG version and the original from archive.com.
Here’s my $0.02 so far. The two versions play very similarly. I think you’ll get the Z experience no matter where you play it so don’t stress the decision. Here’s the differences I’ve noticed so far in order of impact.
GoG Version plays very easily on my tablet, in fact using touch feels much more intuitive than using the mouse and keyboard on GoG or DOS version.
GoG version has a much more zoomed out game display meaning you can see more of the map at once. I think this also results in the game feeling more faster paced.
GoG is missing some of the original artwork. Menus were redone for mobile/touch and looks extremely bland compared to the original. Also the DOS loading screens have additional graphics I didn’t notice in the GoG version.
I had an easier time understanding the cutscene speech in the GoG version, but maybe that’s just a DOSbox emulator thing to tweak.
Is the GoG version a lazy PC port from what was obviously intended to be a mobile remake? Well… yes, but it’s not as terrible as the reviews make it out to be. Is it worth shelling out the money for ($7 US)? I don’t think so unless you have a touch tablet you want to play on the go or in your bed.