Cool thread, lots of great ideas. Here are a few thoughts.
Declaration of Spoils: I much prefer the idea of using a card over stating it verbally because it would easily allow the mechanic of having that card face down until the battle is resolved. In an attack why should the defender know what you're going after? He needs to make some calculations/guesses and decide his defense based on his understanding of your position. aybe giving up X resources isn't that big of deal to him right now (compared to losing forces or getting kicked out) so he'd hold back his cards in the fight. Yet that's not very realistic, to know what someone's attacking you for unless -- to add more complication -- there was some kind of diplomacy card/effect where you could sometimes see what he was going after before committing cards. I think that would add something cool, anyway.
Ties: How are speed and attack/defense ties resolved? My suggestion would be that speed ties go to the attacker and attack/defense ties result in a successful attack/counterattack.
Retreat: Is there some option for the initial defender to retreat? Perhaps if he has the higher speed he could retreat, leaving something behind (either resources or vacating the space). This makes speed easily as important as attack and defense.
Maximum Cards Played: Is there a maximum number of cards you can play in combat? I would think one card per unit would be a logical maximum.
Great combat system, it sounds like fun.
I suppose this is something of a matter of personal preference; is it better to have the defender be deciding how vigorously to defend the territory based on perfect information, or should he be guessing? I think it could work fine either way, it will just have to be tested to see which seems to make the combat work best.
A tie in speed will go to the player who initiated combat -- which is fair, since he had to pay resources to initiate the fight. I currently have that you have to exceed the defense value to score a successful attack; it could just as easily be "equal or exceed". Again, maybe an issue for testing, but a good issue to keep in mind when writing the rulebook! (Arggh, I hate making rules for ties!)
Currently, no. I don't think there should be, because again, the attacker paid for the privelege of attacking, and so for the defender to avoid the fight seems unfair. Although, I do like the idea that a possible benefit of Speed is getting to avoid the attack if things look not so rosy. In practice, though, I think retreat rules are not something I want to include in the game; I don't think they're important enough to justify the attendant exceptions and such that accompany such rules.
The way I have it now is that each player can add 1 card to the battle, and can, by use of a special benefit, add up to 3 more cards. In practice the base may need to be 2 cards to make things more interesting. The bottom line is that these cards aren't meant to be the battle, they're just meant to shape the battle; to make it more interesting. If you want to have a greater chance of combat success, the three ways to do that are to either have more troops (but which costs more to initiate battle), to hold onto your "special benefit" that lets you play more cards in battle (but which costs you the ability to use other special benefits) or to advance technologically so you're pulling better cards.
Thanks, and thanks to all who chimed in. I think it will fit nicely into the larger framework of the civ building game, and will help shape some of the other decisions you'll be making throughout the game, which will be nice.
We'll see how it works in practice! Hopefully a playtest of the full game will happen in October. I'm still hashing out whether I want to add a political mechanic such as what I described in the thread "political mechanic", but other than that, the game is done and I just have to redo the prototype with the new components such as the new combat cards prior to the playtest. And after that, I'll probably overhaul the whole thing again!
-Jeff