Hello there, i bought the GoG version too now, but first thing revealed is that it looks Pixelated.
I had played the 1.8 version of Dungeon Keeper (Original) and get it actually to work (without Hardware mode)
and it looks more nicely as gog version.

also i missed the Commandline parameter function -32biteverything bumpmap etc. where i can use it ?
Higher resolution also seems not to work anymore over Regedit.

you can see it on the Screenshots, ignore some Texture displacement its because of "Working anisotropy" see on floor or because of "High res textures (1) in registry", you can see on the table its more smooth and its overall more Anti aliased then in GoG version , because of what is it ?

Edit : i tried to force Antialiasing to filter the Fragments on GoG version trough Nvidia Panel , though its not working. maybe over Nvidia inspector if i now what are exactly the Compatibility bits.