Yep. Basically, the scenario is OCC Always War. Normally, at Diety difficulty, this would be suicide....
The Gen'Shar are actually the Romans (so I get the Evil Red Color), and begin the game with all technologies through late Industrial. I then took away the Roman Legionary, and also denied them the ability to build Settlers.
Culture flipping is turned off, as are all victory conditions except Conquest.
In story terms, the Gen'Shar actually do understand the ideas behind Replaceable Parts, Synthetic Fibers, and Computers. In fact, they understand far more than is actually present on the Civ 3 tech tree. But these wayward colonists don't have the vast industrial base needed to build the highly advanced components used in their hovertanks and other assault vehicles. So they have to research advanced weapons over again, and adapt them to conquering Earth.
I took a liking to this idea ever since I first played Master of Orion II, and got slapped with that first surprise attack by the Antarans (a highly advanced race, wielding terrifying weapons and attacking you from another dimension, seemingly with impunity....)