Okay so I have been thinking a bit about this topic. 

Since everybody is all hooked up with tech systems, combat systems, I figured I would think a bit about this. It is a rather critical area of the game that will have a rather large impact on how each race plays. Or at least it can become such a system. 

I am sure many of you have noticed by now various issues with influence, manpower, and how invasions work in general. 

My general observation is that there is not really any point in doing invasions currently. You either have control of space and will siege out the enemy in 3-5 turns, or you invade earlier and fight for 3-5 turns loose a lot of troops and get the same outcome. (Your experience may wary but stay with me)

Currently loss of manpower on your ships is just annoying and since it take about the same time to siege down as it does to invade from the start... it is a non choice. 

I have thought about a few ideas for extra features that will spice up this part of the combat mechanics. 

Boarding: 

All ships have a troop count already. It makes sense that a military vessel will have troops on it, and I figure in space it would only be prudent to have ships maintain their own battalions etc. 

I think it would be interesting to have a boarding mechanic. It would mean that the manpower count on ships would actually matter, it would be a ressource you would have to protect when you invade into enemy territory. 

It could be achieved by a single support module on ships (think boarding capsules), and then in the close part of a combat phase, one could decide if it should be used or not. 

I am sure all the craver players can see the benefit of such an approach, but in general I think it could add flavor to all existing races, as well as the ones to come. But more vitally it will mean manpower will be a ressource that matters. 

One thing I do not want to suggest however is that you can take over enemy ships... for the sake of simplicity, it would be enough to just say that a succesful boarding crippled the enemy ship and it then blew up. (Also in the future I think ships would rather self destruct rather than be taken over... It just seems like a sensible thing to do)

Also it would allow races who do not just speed to era 3 and get doomsday laZors to have a fighting chance... the old proveb "You can have the biggest gun in the universe, but what good is it, when you are getting your face smashed in with a rock" (it goes something like that! )

Invasions and Planetary defenses:

Currently the attacker have ALL the advantages... invasion is effectively just this... .park in orbit.. press the I win button after a few turns... this is just boring! 

When an attacker want to take over a fortified planet, he better have brought enough stuff, since that space rock is most likely armed to the teeth, and should bite back! 

Planetary defense structures should matter. For example any kind of space gun or nuke array, etc. should actively damage the enemy fleet for as long as there are defenders still alive. 

This way building shields or other defensive structures that just add manpower (or directly increase the amount of turns it takes to siege) would matter much more. 

The major thing I would like to propose here is that you can NOT just park your fleet in orbit, and then kill off everybody and capture a pristine planet. 

I imagine that invasion will be sort of like it is now but with more "cards" to play

Depending on what sort of system defenses you have there will be certain defensive tactics to employ for as long as you have those structures. The attacker has to win by destroying these, gradually taking over the system. 

The attacker can decide the level of destruction he want to employ... after all having space supremacy has to have its benefits. The more force you decide to employ as the attacker, the greater your bonus, however you will also create a larger permanent FIDS penalty to the system for the more severe cases. (We already have FIDS depletion for cravers, this would be the same modifier with a different name, so easy to implement I would think)

I also imagine that you would be able to start the invasion with enemy ships in orbit.. however then you are limited in the amount of cards you can play as the attacker. NOT having space supremacy is not good if you are going to invade something! 

In short I imagine invasions as something that should take several turns (depending on how heavily fortified a system is) it should not just be "park fleet here... press I win next turn". 

I hope all of this made sort of sense and I look forward to hearing some input! :)