Total Mayhem takes Total Annihilation, bugfixes and extends it the way Cavedog might have. Early game pace is quicker, many new units added (longtime players may recognise some 3rd-party units), including a whole new 3rd tech level tier. Existing and added units have been bugfixed, rebalanced, re-modeled, re-textured and re-rendered to equal or exceed the standard of the original TA units.
Shorter video showing the Core T3 "point defense" (it's got a pretty huge range), the Nightmare. Dark energy. Daaaaaaaaaaaaaaaark.