I've been thinking about alternative win conditions, but I don't have any bright ideas yet. I think the score based system is a good idea, possibly better than the current one. The problem, I think, is coming up with a system that both encourages player interaction, but also is not prone to "runaway wins," because those are annoying.

I very much like the idea of some kind of live statistics that indicate everyone's progression towards the end game, assuming you can influence the outcome as a result. Another aspect of the current system that feels less than ideal is the fact that the inevitable win is going to come out of nowhere. What I think would be really neat is if everyone received reports when a player reached certain milestones towards victory, so that they could react and maybe form alliances against that person to beat them back down, etc.

Another half-thought I had, although this would be tricky, is to give effectively defeated players some kind of "nuclear option" that would have a significant effect on the rest of the game. Again, I am trying to think of ways for all players, even the ones who aren't able or willing to be hardcore about their strategy, to have some agency in the outcome of the game. I'm not necessarily thinking they should be able to detonate their homeworld and take out half a sector, but maybe something like pledge their resources to another player or something, or allow themselves to be assimilated by the some AI Borg collective that gives them some interesting powers but removes them from victory contention.

Anyways, I think at the very least you need a scoreboard so that that everyone has some feeling of progress at the end. When only one guy can win, 149 people have to lose, and to lose a 2 month game with nothing to show for it is kind of sad. With a scoreboard, at the very least you can have micro-competitions between local players and that sort of thing. If I know I'm not going to be #1, I can at least focus my efforts on finishing ahead of my neighbors.