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.
A demo (animated gif) of the Zephyr's shield in action. The Zephyr's shield absorbs 67% of damage! But if it takes more than 12 hits in 12 seconds the shield is depleted and the unit takes full damage thereafter.