Dune II, a real-time strategy game released in 1992, was as you may guess based on Frank Herbert’s second book in the Dune series. I didn’t play it at the time as I still owned a C64 at the time but I did play it before the decade was out.
In the game the player must harvest spice, return it to a refinery to convert to credits which are then used to build more harvesters or military units. Your military units are used to defend your harvesters and buildings and also attack your opponents. You control one of three opposing houses with the ultimate aim of conquering the other two.
Dune Legacy is a modern Dune engine that will allow you to play the original game with modern controls and higher resolution graphics. As well as Dune Legacy there’s also Dune Dynasty based on OpenDUNE.
They all require the original game to run but if you search carefully you’ll be able to find it online.
I haven’t played much of the game yet but it plays much the same way I remember in the past. Go get it if you’re a fan of RTS games. When you’re finished with that have a look at OpenRA, an open source implementation of Command and Conquer: Red Alert.