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.
The Tempest for version 6.9 got a big update... The rockets are gone, and the Tempest gets a massive assault lightning weapon instead (the Tiger assault tank has two of these). The main gauss weapon is now a secondary weapon for close-range attack... these things are deadly. Model and concept was originally by Bedlam Design. Remodel, new turret and new buildpic art by gamma.