Also OpenRA is an engine so is supports Dune 2000 to some extend. This game is less famous but I love the tactical opportunities offered by the various type of soil.
Dune 2000 was my childhood RTS and deserves way more love. Brilliant live action video cutscenes, music, and unit design. I've always found it to be more interesting than the Dune world in general
OpenRA rebalances the game significantly, improves the AI, and greatly modernises the interaction with units.
They both have their place and utility.