good reminders. IG2 was excellent.

Espionage system should bring revolution.

kind of mixing of what you want done - you can add 50% of bribery, 25% of coercion and 25% of randomness to get enemy scientists to hand something to you...

you could and should pack it into mini quests like FE has; mini quests that reveal or bring something forward to players/gamne/locations etc...

It would make all the games different.

I hope they also go with stamps for galactic regions to make mini scenarios in parts of those places..

diplomacy needs far more then before....

It would be cool if the espionage system was integrated enough that you could give spies specific, detailed missions: 

• Blow up a specific planetary installation. 
• Disable a specific planetary wonder for 10 turns. 
• Sponsor pirate activity in Krynn space.
• Infiltrate enemy fleet #3 and be ready to perform a sabotage there on command. 
• Shadow the Torian ambassador to Terra and report on their negotiations. 
• Knock out the Drengin Empire's long-range communications, blocking any diplomacy attempt they make for the next 20 turns. 
• Stage an interplanetary incident to worsen the relations between the Krynn and the Terrans. 
• Fake a government corruption scandal on Earth, lowering the population's morale.
• Steal Lasers IV from the Drengin and frame the Torians for it. 
• Protect our research into Mass Drivers - don't let anyone know we even have them! 
• Secretly spread the Drengin super-flu we produced to every planet they have.
• Support the rebels on the planet the Drengin just conquered, giving them food and weapons!
• Infiltrate Krynn Scout ship #2 and make sure no planets they encounter are reported as colonizable!
• Infiltrate the Terran Espionage Center and find out what missions they're planning against us! 
• Fake scientific reports that Sol will go nova in 25 turns, making people there flee before our assault on it!

Or you could put the Espionage Center on autopilot on goals like: 

• Sabotage Torian trade routes.
• Hide the full extent of our empire. 
• Steal Research. Any Research. From anyone. 
• Make people unfriendly to the Drengin.

I've always believed, in order for espionage to work, it has to be a victory condition. I'm expecting a very hardcore and in-depth espionage system this time around for Galciv3.

So, if your going to put money in espionage, it's going to have to cost you so much that you won't be able to spend money in other areas especially in buying or building ships etc.. Basically, if you want an espionage victory, your going to have to take a risk in the right moment(s) during the game to halt your military/technology/diplomatic progress completely in order to shift the tide on your side by investing in espionage whether it is (sabotage/theft/mutiny). The AI would then determine how much of your espionage did you use to weaken your opponents to a point where they can never rebound, thus giving you an espionage victory. Just like a technological victory where when you reach a certain point, you would get a tech victory and so on. 

I think you should be able to overthrow planet's government with espionage.
Install enough people in their government system and flip the planet.

In combination with cultural influence this could be potential tool against more militaristic, powerful races.

However, this should not be as easy as cultural influence. Should take long time planning and investment.

I'd like to be able to just create revolts in planets of major civilizations and make them become independent/neutral, with bad relationship with their "parent" civilization.

It's called counter espionage

I am not sure you need an espionage victory condition if you make it powerful enough that it can allow you to achieve the other victory conditions

Espionage should allows you to:

• destroy (no one gains), copy/replicate (both side gain), or steal (you gain and the other doesn't) research production, social/military production, or credit production
• disable, destroy, or convert ships or planetary forces
• hide the location, makeup, quality, and quantity of your planets, ships, and star bases
• mitigate the political fallout of negative actions and amplify the positive benefits
• decrease or increase influence
• decrease or increase moral

It should be possible to direct each action as a galaxywide effect or localized to a specific ship/planet. 

You should be able to decide if you want to decrease or increase the influence or moral of your own or enemy planets.  There may be scenarios where you want to boost another races influence or moral.

It would also help if there are common minor random events that would duplicate the effects of these actions so that a player does not automatically identify them as espionage when they happen.  Introducing some randomness to the production system would help as well.

How is this different from a research victory?

The espionage victory conditions I have come up with are:

1. Corrupt X% of all production in the galaxy for Y turns or
2. Setup puppet governments for each faction.  This would be controlling enough votes to always win a vote.  I am not sure how this would work with a dictatorship.

If they included something like a king unit, then you could have an espionage victory from successfully assassinating every race's leader before they can elect a new one. Causing the universe to descend into chaos.

I'm like picturing spys and leaders all being actual units you can move around. You could try keeping your leader in isolation on a fortified world to keep them safe. The hard part about letting the player react to an espionage victory is the espionage. It's all about being secret.

Of the top of my head, this is what was possible in IGII;

- Training (different levels, higher level of training cost more and takes longer)
- Gather intel (planet locations, fleet info, tech info)
- Steal (credits and technology)
- Assassinate leaders (causing instability in the empire, planets defect to other empires)
- Counter-intelligence (enemy spies get wrong info)
- Hunt enemy spies (hunt them down and then either kill them or try to turn them; double-agents)
- Sabotage (destroy ships, buildings or starbases)

I love that aspect in elemental.

I am a tad worried that staging revolutions might just feel like an part of the combat victory then a whole thing in itself.