I find playing with AI 'very hard mode' terran or protoss still alright with uh, basic zerglings rush and infestors. Never really count the way i build it. Just spam zerglings rush like old sc1 meanwhile stocking up infestors and disturb the AI none stop with the infestors. Included building ground cannons, forgot name == sorry 'spine crawler?' right in front of AI's base exit. Usually able to bring it down without much problem, unless I fail to defend around the 1st~3rd attack from AI. But never tried vs a zerg. Though I never tried it before, but I think such a way vs-ing humans are useless. Just for fun though ^^