Tried Voidcraft for 2 days straight singleplayer. So far I haven't had any success whatsoever to defend myself against the huge mass of Zergships that spawn around the 18min mark. I tried both ships, different weapon combinations, different strategies. Best results were had when I flew straight into the enemy base and camped the front... which ended when zergs went around me and killed my baseship behind me. I lasted roughly 2 minutes longer than usual.
Voidcraft is a fun concept but it is an utterly frustrating game, especially without human players to fight against.