To be honest I'm not entirely sure how the algorithm for repairing works in PA, but from I've experimented it seems pretty clear that the more metal cost something has, the more it costs to repair. This seems fine on paper, but ingame it makes some really stupid things happen. For example, the Angel is one of my favourite units, but I can't use it. Not because it is overpriced and can't even reclaim (which it is) but because how badly it works. If you ever tried to use, say, 3 angels at once, you will discover two things: 1-Having more than 1 sucks, because they all shoot at the same missile at the same time and overkill it. They waste a lot of shots, fire more than necessary and lag the hell out of your computer while doing so. I wouldn't mind it, but 2-You have to turn them off so they don't repair. Angel has a buildpower of 120 metal/s. That's the highest in the game by a lot. You can't possibly afford to have it on and near a battle, because it'll start repairing **** that will die anyway, possibly overkilling with its repairs (which I'm not sure but seems like they do. Specially if you have more than 1 unit that repairs) The metal cost for repairing it simply too high and happens too fast to be sustained by your economy. It's very situational. Also, repairing high cost units (which should be the primary use of repair) is a nightmare. Repairing the comm takes thousands upon thousands of metal. It shouldn't be too easy to do, but right now is absurdly expensive. So, my conclussions: 1-Repairing atm is very bad unless you're repairing very high hp units with low cost, like turrets or orcas. Otherwise it's a total waste of money you'd better spent producing. 2-Trying to repair with high tier units / a lot of them basically destroys your economy in a blink. 3-Repair cost should depend on the amount of HP you're healing, not the metal cost of the unit. 4-If you're repairing it usually it's because you want a) not waste metal producing the same units again b) not give your opponent scrap, so it makes more sense to have repairing cost more energy and less metal.