My Dune 2 clone has the ability to do some of what you want (new units, races, buildings) which you can change through its ini file. But it's still at an early stage of development, so wont offer you the total flexibility that your after at the moment. You can however modify my source code to your own needs so long as you agree with the licence. You can download my dune clone from: http://www.dune.datum.tv