New version up. Designed units are now usable in combat.
Now, thoughts about turrets:
One thought I had was to have separate structures that you'd build from the Construct menu placing them down. They'd be based on the unit types, but be immobile and have extra range and/or hit points.
But a friend of mine came up with another idea, borrowing from Homeworld 2, which is that "turrets" are ships that will only listen to a single move order, and once there, never be movable again (they'd also be cheaper, have greater range and/or hit points--I'm considering having several built at once, the group costing 1 crystal, but I dislike that solution due to what happens when they die: either it's a 25% chance to drop a crystal, or none of them do, as I can't have them each drop a partial crystal, just due to how the harvesters are coded: they won't start harvesting a crystal unless they can both carry a full crystal AND there's a full crystal
to harvest. Or they cost no crystal to make).
Another thought is that buildings themselves have guns--like AI War's guard posts. Or the Spire Cities. I dislike this solution conceptually.
Yet Another Thought is to have "turret hubs" which use 1 crystal (for power) and then can support 4-8 turrets that would need to be built within a certain radius (I've got several games in mind that this might be comparable to, such as Perimeter or
Space Game Missions). This solution seems most workable, yet the least satisfying.