Before you read any further, No, this does not mean that we're just going to add new defensive structures into the game that are super powerful. That would be easy to do of course, but thats not what we're trying to do with this. No, the term Super Defense is based around the idea that after a certain point a player/enemy base will gain access to a form of "Defense" that makes it much harder to attack in a specific way or fashion.
Lets talk about the O3 and the EF here for a bit shall we? We'll start with the Scrin.
The Scrin are an invasion force. They are not concerned about building massive bases and holding ground, instead their entire army is based around the idea of devouring the enemy as they go so they will not have a defensive super weapon. They are a pure offensive force so it wouldn't make since to have one.
Nod's "Defensive Weapon" is called the Orguss Effect. Basically what happens is once you have a Temple of NOD built all of the stealth Generators will output a "no-fly-zone" Ion Ceiling. In effect if any air units fly through this storm they stand a very good chance of getting destroyed. Ground units are not effected by this power. It leads to a simple case of "Ok, if we don't take that Temple of Nod out we are going to have to hit Nod with a ground attack, air's not in the equation."
GDI's "Defensive Weapon" is something that I particularly find amusing. Once you have the Ion Cannon Control Center built any enemy GROUND units that are seen attacking the base around the Ion Control Center will be targeted by a limited-field Ion Cannon blast. Think of it as the Ion Cannon Direct fire power from the 2nd war. There will not be a blast radius on this shot and obviously if your opponent is a fast moving unit it won't hit either but for the most part this means that your Ion Cannon could potentially defend an entire base by itself from slow moving Avatars and Tripods. This also means once GDI has this up your best bet is to hit them with air or stealth units to get inside the Cannons fire radius.
Earth Federations AW force again isn't going to qualify for a Defensive Super Weapon. We're up in the air about UC if we want to give them one or not. However Seed has always had this kind of thing in it from the original design. The Artimis Shield.
The "how" is still up in the air about this but basically it is going to work like this. The Shield Generator will activate the shield whenever an enemy unit comes in range. This will have 2 effects. Anything that is inside the shield when the effect go's off will be given invulnerability to show that they are inside the shield. Anything on the edge of the shield (the enemy that triggered the shields activation) will have its speed reduced to 5% to show that it is trying to get through the shield.
The Shield will not work against super powers like Ion Cannons. Also again the shield will only work if it can see the enemy comming like aircraft or units. Finally the Shield only works for a certain radius, like 200-700 so once an enemy gets close they can destroy the structure and take the shield down. Again stealth is important here.
I hope you guys see what we're trying to do. Some of these ideas still need to be fleshed out but in the end I think this will add that last level of stratagy that a CNC game should have.