Supcom had this wonderful feature where, if you lost a structure, you could rebuild the same structure on top of it and save 50% metal. This was very useful for recovering from a situation where you got evicted from your base and had to march to an enemy one and kill them (in an FFA), allowing you to quickly make use of their already existing infrastructure.
I would change it to the resurrection bots in TA. They pump energy and metal into wreaks and reanimate them. However this has been talked about a lot and almost everyone is in favor of it. Probably should have looked to see if it had been talked about before.
Resurrection bots doesn't seem like a very good idea. Think about it, the scale of this game. If these bots are going to have any effect on the game then they must resurrect entire armies, and to resurrect entire armies you need an entire army of bots, and that's just tacky. Unless one bot can resurrect an entire army, then you need to increase the cost of the bot. So now you either have an experimental or an OP bot.
