I have found the best way to beat every difficulty even Insane (which is not insane at all). Only use and upgrade support (far left units). Also upgrade income. I have found it to be very affective, and also be aware that the comp. always does a special attack shortly after upgrading tech. So don�t have 10 guys out, unless you can afford it. I have been able to beat every diff. using the technique. Even before upgrading to the final technology. Give it a try and see if it works for you. let me know in this topic. Thanks
