Additional Eminent Domain possible expansion thoughts - Fighting with other players!

I'd considered once that maybe Warfare, since it was allegedly 'easier' than the Colonize, could be a sort of Scorched Earth thing - when spending armies to attack a planet, you leave one of them on the resource slot, blocking it up so it cannot produce. Rules-wise this means when you flip a planet via Warfare, it gets -1 resource slot. I decided against this because there aren't a whole lot of resource slots, and I wanted Warfare + Trade/Harvest to be viable.

However, today it occurred to me that there could be a Technology ("Scorched Earth Policy" perhaps) that says "Warfare costs are reduced by 1. When attacking a planet, leave an Army token on it."

The standing rule could be that armies on planets reduce the storage capacity by 1. I tossed around the idea that an army token could reduce capacity, but be worth 1 VP... I didn't like that at first because thematically it should be bad to have scorched earth policy, not good (for scoring).

But then I had another thought. Suppose you were allowed to attack other people's planets. people always want to do this at first, and some complain in games like this and Race for the Galaxy that you cannot attack an opponent. So I thought, what if you could - what if an ATTACK action allowed you to attack YOUR face down planets, or ANY face up planet in play. The "cost" to attack a face up planet would be the VP value of the planet (maybe), and the effect would be to leave an army on it, which as has been discussed, would keep it from producing as many resources. That could be enough right there - your opponent is trading like crazy, maybe you want to go blow up his Silicon silo and reduce the amount of VP he's getting.

With that in mind, it might be neat if the Armies on planets WERE worth 1vp, because then you could attack your own face up planets for a benefit (if you're not planning on harvesting anyway), and it would be a deterrent to attacking other people's planets - you could take away their production capacity, but it would give them a VP. I'm not really sure this is necessary though, just spending your turn hurting someone else and not helping yourself might be a good enough cost (those Armies could have flipped a planet for you). Also, it doesn't hurt your opponent's score if you attack their face up planet, it just hinders their trading ability. Perhaps if you get another army on there the Icon could be disabled or something.

Anyway, I like the way the game works without attacking each other, but I think I might add this in, maybe as an optional rule, for the expansion - that is to say if I test it out and like how it works.

Summary:
Rule: An army token on a planet card reduces the storage of that planet by 1
Attack: You can attack a face-down planet in YOUR empire, or ANY face-up planet in play. Attacking a face-up planet costs 1 Army per VP that the planet is worth. When you Attack a face-up planet, put an Army token on it.
Tech card: Scorched Earth Policy - Warfare costs are reduced by 1. After Attacking a planet, place an Army token on it from the supply. (Planets have -1 Storage per Army token)