Conquest of Solar Systems

[Greydog]

A Declaration of War is still the best reason to institute a waiting period before an attack. The defender could accept the declaration at any time during a set period (say 24 hrs) beginning the war immediately. If the was no reply before the time period ends then the attacker can begin. Any colonies or structures are not covered by a jurisdiction are unprotected and may be attacked without a declaration. The time period would work across an entire empire and not just a single system. Once it's up, any of the defenders systems could be attacked.

The idea of this was discussed in the past, and not only did people seemingly hate the idea, it also has a lot of issues.
See: (Idea thread) Formal War Declaration

We didn't discuss this in the thread, but a lot of exploitable holes come up when you think about the idea further.
Examples:

• Attacker declare war on your empire. You surrender all your cities to a neutral third-party empire.
  
• Attacker declare war on your empire and all third-party neutral empires. You create a new empire and surrender your cities to it.
  
• Attacker creates a new empire and transfer all their warships to it. You want to fight back, but the waring empire has no cities for you to attack.
  
• You declare war on attacker's main empire. You are now considered the aggressor in that war and the attacker surrenders their cities to an ally.
  

So in the end that idea was abandoned and I had this fantastic idea about declaring war on a location instead of a non-physical entity such as an empire. I made an idea thread about this idea and it has gotten popular, I suggest you read it.
Here: (Idea thread) Conquest of Solar Systems

Planetary shields could be a thing but not as something that just appears when the planet is threatened. It should be a couple of huge ground emitters on either side of the planet that are tied to a series of orbital emitters. It should use massive power, Need massive resources, and take forever to build. City shields should still be there as a (more powerful) second layer that needs to be cracked.

There is no universal rule saying that a planetary shield generator has to be huge, consist of multiple parts or even be a physical structure. I know you might have an opinion about planetary shield generators being huge and impressive, but that doesn't matter at all when we are discussing gameplay mechanics.

As I already mentioned a few posts above, the ancient ringworld builders could easily have created super-duper advanced planetary shield generators that automatic protect every single world in the entire universe. (#27)

Well, in the first part you could simply make the declaration of war take precedence over other further diplomatic actions until after the declaration has been resolved. If an Emperor quits their empire, a new empire cannot take over without first responding to the declaration. The time period would not be reset and if a response is not given the attacker may proceed as they wish. Or (even harsher) the empire is considered "ungoverned" with an instant loss of morale across each of it's cities. at that point they could all be claimed individually by planting a flag. This would most likely set off a land rush with each side trying to grab what they can. I can't help but think that are no participation trophies in war and gameplay should reflect that. 

While "realistic" is not what we're looking for "plausibly realistic" could be, which is how I look at it when thinking of these suggestions. With that, I tend to think that a real enemy bent on conquest would simply scoff at the notion that changing the name or leadership of a civilization would keep them from their goal. Instead it would possibly spur them into harsher action. But because this is a game we need a "plausible" reason to mitigate that mechanic. My suggestions are meant to slow the advance enough to allow players time to respond one way or another.

My shield ideas simply reflect a need to make the mechanic more substantial and less "magic". I have no issue with the ancient tech shields that you suggest, so long as it needs to be discovered via exploration like a ringworld is. After discovery it could be researched and updated like any other tech.

An empire bent on war is going to wage war, we shouldn't want to stop that, just deter it. As you say, how a mechanic works is more important than how it is delivered. At the same time the mechanics themselves should be almost invisible. It's the wrapper we place them in that creates the lore and ambiance of a game. It just so happens that we, the players, get a large input into what that wrapper consists of, so just because something has been discussed before, doesn't mean the discussion is over.