Maybe a combination of these?

- decrease combat loses (like 50% your fleet will be damaged for 10 turns instead of destroyed)

- promote being in several places at once for several turns (like blockade of a planet, ground invasion)

- relatively high free defence for planets (not in terms of dealing damage to invading ships but as an ability to hold them off for several turns before the defences break down)

I do think you have to be careful with that method though, as one could prolong combat indefinitely with a legion of tiny scout ships, if not balanced well.

That's why I was thinking of "You can add forces anytime but it will not extend the battle (3 turns)", so, something like the first ship that arrives there initiates a battle and the battle will last 3 turns. The winner of that battle gets "recently won here" marker or some sort of "space superiority" marker which lasts for 5 turns during which that player (and that player only) can pass through that system ignoring battles. Hmmm, I'm not sure... Or maybe make the battle last just one turn if the enemy is below 20% strength (or even better if he gets annihilated by the first salvo the battle immediatelly ends)?

After thinking it over I say my idea has no sense :D Way too complex & confusing. At least my approach, I'm not saying one of you can't invent some working "multiple turn combat" :)

Yeah, I could see that being an issue, it's unique, which always makes things harder, as you have to pull all the stops in the UI to really sell it to someone not used to it.

I think you should give the upkeep stuff a try. As long as you avoid some of MOO's pitfalls, which shouldn't be that hard, since the MOOs were fun games, but they weren't exactly well balanced.

i'm seeing MOO:II mentioned several times, but not how they countered this, which was with a building that slowed down all incoming opponents-fleets.

There was also a possibility of disabling retreat during combat, meaning an overextending opponent might be forced to waste his fleet on your defenses.

I don't think MOO solved the stack problem rather it created it. in MOO 1 you could build multiple ships per turn and ship types stacked so in a single battle there might be a stack of 10,000 small ships and you might kill a few thousand a volley with your spatial disrupters.

In MOO2 ships no longer stacked but you still had large AI Fleets. Generally they would have massive fleets with 40+ ships and just move that from planet to planet. Depending on tech you might be able only be able to kill 1 or 2 a round or 1 per shot. That is probably why the game included the stellar converter weapon which more powerful then every other weapon combined. It did 2000 damage never missed and could destroy planets the second strongest weapon only did 50-100 damage. Many times in MOO2 late game planets would get stuck in lengthy blockades where you simply didn't have enough combat rounds per turn to kill all the enemy ships. The computer opponents cheated so they could build and maintain far more massive fleets then players could build.

And you couldn't use non-tactical combat because it didn't resolve to the same out come as tactical combat on auto. The non-tactical combat would let a large weak fleet win against a small fleet of high tech ships they couldn't damage in tactical combat.

I don't think MOO solved the stack problem rather it created it.

MoO II is still my favorite 4X space game!

You might consider a story fix for this particular issue, as an example:

Only so much ship tonnage can pass through a wormhole in a specific period of time before destabilising it and making it impassable (or highly risky to further traffic) for a fixed period of time. This would not negate sending multiple fleets through different routes to attack the same target but in my opinion that sort of strategic/tactical game play of fleet positioning would be something you would want to encourage. What would be an additional factor for consideration if using an idea like this would be the effect on other ship traffic being affected i.e. merchant/commercial traffic or even enemy fleets in pursuit.