Perhaps make invasions last a variable number of turns, allowing for the planet to be reinforced by allied troops.
You could choose from a variety of warfare types, like siege warfare, where your troops dig in, and try to slowly advance one step at a time and take the enemy citys, using trenches and lots of artillery, It would take a few turns, and it would run the risk of being counter-attacked, but you would have large advantages. good for when you have a large fleet in the area to ward off enemies but don't have too many troops.

Or perhaps a blitzkrieg style attack, where you use heavy amounts of aircraft carried troops to quickly move in and attempt to establish control. It would be more risky, but only take a short time, so there would be little chance of being counter attacked. It would be good to use if you had few ships, but lots of troops.

Maybe you could choose from between three types of warfare and specialize from there, like choose between blitzkrieg (takes 1 week), Normal (takes 2 turns) and siege (takes three turns) and then go into thinks like mini soldiers and tidal disruption etc, which would keep it simple, but add some more choice and make it a little more realistic.

Agreed.

I agree invasions are too quick, if you send in 20000 (20 billion troops) chances are you'll win, but in one week? hmmm, when you will you can move 18 billion to the next world and so on in one turn. I think also multiple turns per invasion say between 3 and 10 based on the number you send in, also allow you to pump in more troops and the enemy to send in more too, not a massive change for the game, adding a little bit more complexity and requiring a little more thought.

for those that like fast games have it as a toggle switch in the settings.

I would truely pay for this mod on it's own.

I agree with neilo about keeping the focus on space. Yes, invasion is a big deal at the local level, but if I'm playing the game as the leader of a huge space empire spanning multiple systems, I want to focus on the big picture and not the messy details of each invasion. That's what I have minions for. To do this right, would require practically a secondary game within the game. I'd settle for just some eye candy updates so the invasion process doesn't look so primitive and silly compared to the rest of the game.

Another thing... if you go too far down that road; deciding on blitz attacks, moving troops to besiege cities etc., you're getting into a level of hands-on control that I think many people would rather see go into tactical space combat. Not me... I'm fine with the current setup, but it's a valid argument. Why have that level of control on invasions, and not your critical space battles?

I would have to side with Neilo. And really, realistically, if a race has broken past your starships and other defending platforms (now there's a thought) then the writing is on the wall for your planet anyway.

One suggestion I can think of that may work would be a Conqueror penalty enacted on worlds for a set number of turns, and maybe a higher chance of a world reverting to its parent race if its not garrisoned with ships (ala the Civ games) or other improvements and the such

I'd love it if invasions took some time to carry out. Greater distinction between the invasion techniques could follow from that, since some end battles quickly (orbital bombardments and tidal disruption tend to do that) while others take a large amount of time (traditional and information warfare). More options could be added, as well. Off the top of my head:
*A quick, dirty invasion option that provides a PENALTY to your troops
*A drawn out seige that practically guarantees victory

You're applying a human history model to space combat between different species. We've never seen a major species vs. species conflict before, with both using spacefaring technology. Total extinction might be the only way to take over another race's planet, and that wouldn't take much time if you have complete control over the stellar neighborhood with your starship fleets.

Even a more charitable race would have an overwhelming advantage in an invasion. Space superiority is handy that way... it means you can drop your troops anywhere, anytime, with fantastic intelligence, AND you have heavenly artillery on demand.

The problem is it would change the system. E.g. if you know, that your enemy has attack factor 50:3, would you send more troops there? I guess not. The next thing, you will want to have the possibility to change this too. And it means rewrite AI from the scratch.

I agree with Firebender. it is just not realistic that it would take only 1 week to eradicate a population.

There are many things in this game that aren't realistic, but too much realism just leads to micromanagement headaches.

The main question for me isn't whether a one turn invasion is realistic or not... partly because I can easily imagine rapid sterilization from space, but that's not even the main issue. It's mainly a question of whether it would add anything to the game other than one more thing to keep track of. If the results are the same either way, and it's just being stretched out over multiple turns for the sake of "realism" (with no added tactical control input from the player), then it's just unneeded micro. It's a distraction from the galaxy map. And if the devs did include more hands-on management of a multi-turn invasion, now we're in mini-game territory. I suspect a lot of people would prefer that effort going into tactical space combat. So I like it the way it is: invasions succeed or fail in one turn, and I can move on to other things. It just needs to look less like a cheap cartoon.

Anyway, just one person's view. I know some will disagree, but I thought that view should be represented.

I too would like to see the invasion screen get a long needed overhaul. However i as others have said would not like to see a multiple turn invasion strategy/ I also think that it would detract from the main point of the game which is a space strategy game.

That said the invasion cinematic is the letdown of the game and has not really changed, if at all, from GC1. Way past the time to sort out some nice new graphics.

Hey maybe let us design our own landers/tanks in the ship creation screen and then have miniature ones in the invasion screen!