Super Dune 2

Super Dune 2, also called with a subtitle Super Dune 2 The Destruction, is a mod of Dune II created in 1994. There is an updated version of the mod called Super Dune II Classic, published by a different author in 2009. It fixes as many glitches and bugs in Super Dune 2 as possible, while keeping the original feel and features of the mod intact.

The three playable houses in each campaign are replaced with Mercenary (yellow), Sardaukar (purple) and Fremen (orange). The original houses still appear sometimes as enemies. The new campaigns are more difficult than the original and meant for experienced players. Each new house has different characteristics, notably the Fremen can control the sandworms.

Another updated version of Super Dune 2, named OpenSuperDune, is included in Dune Legacy.

Official site
There is an official page only for Super Dune II Classic: http://www.moddb.com/mods/super-dune-ii-classic