Amazingly I have beaten all campaigns and colony missions on hard, basically it requires a lot of patience and saving. For the colony missions to survive the opposing factions attacks all you have to do is build up massive ammounts of material and base before progressing into the next tech phase. Also to ensure you get rare metals as fast as you can you can save, research it, find the nodes, then load the game and just build a normal base near that node, and build up everything. Four common smelters on a mine, 2-3 mines, 6-8 vehicle factories, 50 scientists + 2 adv labs + 2 standard labs. You have to constantly build forces. It's all very taxing and difficult for the colony games, but you can do it. The campaigns on the other hand are just a f***ing b**** to do, but persistance pays off. Play the missions over and over and eventually you beat them.... taxing but rewarding.