I have been playing "Emperor: Battle for Dune" over the last week or so after having kept the game on my radar for a long time and it absolutely lives up to expectations: it's at least an excellent game, one of the best RTS titles at the time of its release, AND it's based on Dune! What more can you want? To see it legally available on GOG? Sure but good luck overcoming the epic licensing issues - still, you brought back "Blade Runner", so there is hope!
Now, if you'll excuse me, I need to go back and play some more... the Spice must flow!