I doubt I need to convince anyone that as of v1.5, the diplomacy system needs a lot of work. I've put some thought into how to make it better, though. What I've written here is a selection of what I consider to be the biggest flaws in the current diplo system, along with suggested mechanical and balance changes to address those problems. It's not a complete list of issues, nor of possible improvements, so by all means, add your own suggestions.
- Alliance victories are way too easy to get. It's literally a tech victory that you can win in the Age of War. Rush Instellar Alliances, build a few embassies/diplo outposts, and boom, you win.
- Thoughts on a solution: The big problem here is that once you get the tech and a race likes you, it's one click to permanently check them off on the victory condition checklist. I see nothing wrong with starting a tentative alliance that way, but you should need a stronger relationship than that for an endgame condition. I would extend the process by creating multiple levels alliance that must be acquired in sequence. For example, you first sign a non-aggression pact (or some new form of provisional alliance), then after X turns, you can form a proper alliance, if you're still on good terms, (this is a key improvement to gameplay depth, since in the current game you can dump on your allies all day with no real consequences) and finally you must form a "Galactic Federation" with all races to secure the win. This would probably be tech-gated at the Age of Ascension; though not necessarily connected to the existing tech with the similar name, it could be. To form the Federation, all allies would have to *currently* like you enough and not be at war with each other. The whole point here is to make diplomacy an ongoing battle, where you have to get people to like you and *keep liking you* for a substantial amount of time, which should be progressively harder as ideologies take root, wars start, and grudges over this and that build up.
- Diplo-boosting buildings are overpowered, but more importantly, they don't make for engaging gameplay. Diplomacy is supposed to feel like a delicate balancing act. You're supposed to be sucking up to one race while trying not to piss off the guy that hates them too much, not robotically constructing buildings until they both like you.
- Thoughts on a solution: reducing the building/module bonuses by about 80% would be a decent quick-fix for balance, but I think these buildings can be made much more interesting by targeting particular races. Diplomatic outposts and embassies should boost relations only with nearby races (bonuses determined by having worlds in their zones, with modifiers for pop and distance to capital), rather than with the entire galaxy. That's a whole lot more logical, isn't it? What's more, the more such outposts you build, the more the other AIs know you're cozying up to that race, so they might get pissed at you if they hate your new buddy.
- Treaties (e.g exploration, research) are very overpowered, allowing a competent player to suck the AIs dry while sacrificing nothing. Rebalancing them should be fairly easy, at least.
- Thoughts on a solution: Exploration treaties can be fixed simply by reducing the cash value the AIs will pay for one. For research/economic treaties, there are a couple things I would do. First, I would I would make the treaty give +25% of THEIR research to you, and vice versa, then evaluate the treaty based on the net exchange (with a modest bonus to the side who actually has the treaty tech). That means an AI with much better research than you would actually demand payment for the treaty. Meanwhile, you might be able to suck some cash off a minor race by proposing a research treaty with them, but you wouldn't get a huge benefit from the treaty itself, and they would actually get their money's worth. Second, I would increase the duration of the treaty substantially, so you can't repeatedly reduce the AI treasury to zero.
- I read a LOT of complaints because the AI hates you when you're weak. This doesn't bother me, personally, but if enough people are frustrated by it, there needs to be at least a tweak in the presentation.
- The AI *should* be inclined to attack you when you're weak, so I don't think there's a fundamental problem here. However, since this frustrates newbies, the negative modifier could be dressed up in a much more palatable way. It's a lot more flavorful to get backstabbed by those guys who said they were your friends (but you should have known better than to trust them) than to have everyone threatening to knock your teeth in, until someone finally does. I'd give the AIs a little more defined personalities, here. Some races, like the Drengin, should be openly hostile when they don't like you (i.e. no change). Some, like maybe the Krynn, should be all smiles to your face, then occasionally declare war seemingly out of nowhere (i.e. reduce the "you are weak/ripe for conquest penalties, but allow the AI a chance to attack at higher opinion levels). Make sure to add some sort of gloating text, so players know this isn't bad/buggy AI. Some, like the Altarians, should simply have reduced/removed "you are weak" penalties, so people feel like at least they've got one soft touch out there.
- The AI doesn't prioritize diplo techs at all or seem to attempt diplomacy at all.
- Thoughts on a solution: force the AI to be better.
One more thing I'd like to see, although it doesn't address any specific flaw, would be a set of minor random events (I'm thinking like the ones in Civ 4) which would influence relations between you and a particular race. For example, you might get an event where you answer a distress call and find a Thalan ship which is dead in the water. You get the choice to a) rescue the crew and send them home (-credits, +relations with Thalans, +5 benevolent), b\) offer to repair their ship, for a nominal fee (+credits, +5 pragmatic), or c) kill the crew and take their ship (+free ship, chance the Thalans find out for -relations, +5 malevolent).