Most people dont understand or like the randomness of invasions, personally i dont like the idea of one battle after a certain amount of time to decide the fate of a colony that was constructed over many days or even weeks.
So lets get rid of the randomness!
A new better and easier to understand system:
after dropping an invasion force it will look like this:
Attackers dropping troops will still be subject to ODS troop reduction penalty when adding invasion force to their stack.
The decline rate is based on the troop strengh of the forces involved. Maybe 10% of troop strengh as damage /h with a maximum of 10% of the opponents force but atleast 1% of the defender.
dropping 400.000 troops on a planet that has a T2 ODS. -> 200.000 attackers added to the stack.
[10% strengh as damage -> 20.000]
The defender has 1.000.000 troops
[10% of strengh as damage -> 100.000 damage -> but damage is capped to 20000 (max damage 10% of the attacker) but atleast 1% of defender (10.000) = so the decline per hour on the attacker is 20.000/h]
It will result in 1.000.000 -20.000/h vs 200.000 -20000/h. The invasion will be over once the first stack is reduced to 0. During an invasion population growth is reduced by the ratio of the attacker vs the defender. 200.000 being 20% of the 1.000.000 -> 20% growth and income reduction.
All numbers are just some suggestion and should only support the basic idea of a constant battle instead of a one drop one battle mechanic. With the suggested mechanic people will be able to blockade planets to stop any reinforcement. Then another cool feature will be “fast and agile” corvettes being able to drop troops regardless of hostile ships being present. (blockade runners)
When troops can be added constantly, some new values or modifiers should be intruduced, like landbased defense structures dealing X damage every hour or increasing the damage dealt to invaders by 20%.
Maybe we can even group forces by alliance:
50% of the damage is always directed at the planet owning alliance and the rest of the damage spread between the other alliances.
Toying with the values can make it so that a battle between even forces will always take 24h or so and a defense force of 100.000 will always be able to defend a planet for 24h no matter the size of the attackers. But something that we should keep in mind is simply the fact that this is a game with alliances so alliances should be able to A defend a planet and B attack a planet TOGETHER. Defense tech will also increase the defenders troop strengh and therefor deal more damage making it easier to defend against defenders.