Interesting discussion.
The best strategy to 'win' the game is start with no NPRs, turtle in Sol and build a balanced fleet, which I never do 
I either start with multiple races so that each one has to race into space to compete, or I give a single player race a reason to get out of Sol (such as some form of disaster). I find the best games are the one in which you face a significant challenge with forces that are in no way ready to face it
Do you think this (the ability to turtle in peace) is likely to change with the new NPR AI? In the past, it's seemed like most of the AI threats (other than Invaders) haven't been very good/aggressive at going after your home system. I've seen some instances of "about to be overwhelmed by an alien horde" in the "what's going on in your empire" thread, but my personal experience has been that pretty much only having to deal with annoying jump gate construction spam (other than Invaders).
Or are you saying that turtling is a better strategy simply because it activates fewer NPR (that by definition will be in contact with your empire) and so it delays the point at which you need to deal with aliens, and so that you'll end up with fewer aliens?
I can see both good and bad aspects to having quicker risk to Sol. On the one hand it adds the element of challenge (and fear
) that you mention, which I like. In this respect, it would be very similar to adding the AI in the first place - the sense of not knowing what's going to jump out and bite you at any moment. On the other hand, it runs the risk of making the game too difficult - I personally would be frustrated if 80% of the time I had superior alien civs invading Sol and killing off my civilization, especially since I almost always do a conventional start. This is one reason I (and I think everyone else) almost always turn off Invaders - they're too powerful for early game.
A few thoughts on game mechanics to address the above (assuming the AI NPR will be better able to build a multi-system empire):
1) I think (maybe not for 1.0) improved diplomacy is VERY important. In particular, the potential for aliens to be (useful) allies instead of enemies. On the one hand, we don't want to end up in the SM2r4 situation where most of the aliens you meet will be your friends and allies, and so the game becomes a case of simply trying to find the most friendly aliens you can (and/or the GFFP situation where it's too easy to exploit the resources of conquered aliens, so that it's cheaper to conquer than to ally). On the other hand, having all the NPRs against you (and presumably each other) encourages the turtling strategy, so that you activate fewer NPRs. So whatever happens, I think a way to make turtling sub-optimal is to figure out how to make activating NPRs a good thing on average.
If you go down this road, I see the game ending up with multi-race coalitions, and the player would need to navigate which coalitions to work with and which to avoid. I think a reputation system in diplomacy would be really important in that case (shades of Crusader Kings here): If you wipe out race C, then races A & B with whom you have contact will have a lower opinion of you. In addition, allied races should be much more likely to help/support you in an offensive war than in a defensive one. Unfortunately, that's probably a difficult AI system to write and make good and balanced. OTOH, it sounds like your new AI might have the framework (in terms of competing needs and drives) to support it. OTGH, I can't think of another point - I just wanted to say On the Gripping Hand
2) It will also require attention to (early game) balance and ability to wipe out other races/worlds. I think you're already going down this road, but it should be VERY difficult to knock off a home system (not just home world), so that if the aliens do find you early in the game they can't just roll over you. I think this is what you've tried to do all along with ground combat. This also comes back to diplomacy - if other NPR (e.g. E & F) that an invader D is in contact with notices D has concentrated forces, then maybe that raises the probability that they attack (although the noticing part hard to rationalize given that the communication model is such that races will only have knowledge of things going on in systems with which they have physical contact).
This segues me to thinking about communications. It would be VERY interesting if non-Newtonian physics introduced an instantaneous communication system that spanned the entire galaxy (analogous to radio in modern warfare). That would you to be in touch with other races with whom you don't have physical contact. There would probably need to be some technobabble about why this only works for races whom you've meet - maybe there's some weird quantum race code/entanglement that means you have to have been in the same system with the other race before it worked, otherwise you'd be able to hear all the undiscovered races out there and be able to eavesdrop on their comms and maybe discover huge tech from highly advances races and .... The "entanglement" technobabble (which wouldn't quite be entanglement, since it would need to be contagious in the sense that one entangled device could pass that ability on to another device) could lead to another aspect of diplomacy analogous to Civilization's "I'll sell you contact with Empire X that you haven't met yet" trade interaction. This would give a lot more power to infiltration/diplomacy/spying functions - if you have the code for another race, they can tell you they're being invaded and scream for help even if you're not adjacent. Similarly, if you can insert a scout ship into another empire, the scout ship (or embassy) can report back even without courier ships.
3) So the way I see it playing out is that the game mechanics are lined up so that:
A) Exploration is good - it gives you new planets to colonize and the opportunity to activate NPR that are likely to be friendly
B) On average, aliens should be friendly, but every now and then you should run into something nasty (like the bugs)
C) The bigger your alliance structure, the less likely other races should be to join it (or any other big NPR coalition). Note that this should be measured in total strength, not just ally count.
D) Global communication technobabble lets the various races have a much better understanding of the galactopolitical situation (how big empires are, who's getting invaded, ....). For example, one aspect of alliance should be that races in the alliance will automatically share com codes for newly discovered races with each other (at risk of a malus if violation is found out), so that the new race can judge alliance size. The technobabble should also (maybe) support knowledge of how many systems colonies are located in, to be able to judge the size of an empire.
E) The incentives to war would be either being meeting bad guys who encroach on your territory, or deciding you're penned in and need to go to war with someone to re-open lines of expansion.
I strongly suspect all of this would be really difficult to set up and balance, especially for C# 1.0, but it's nice to think about....
John
