RE: The warscore thing: You could go to common>war_demand_types>00_war_demand_types.txt and fiddle with the different base costs of the wargoals. But warscore is a percentage, not a flat number. It's just unbalanced as shit because some wargoals are bugged, it doesn't scale well in several ways, and the game lacks both the historical context and the larger variety of methods for engaging with other empires that previous Paradox games have.
That's the fundamental thing, Paradox games are not about conquering everything ever and warscore reflects that, but the current state of Stellaris is such that beyond a certain point you have nothing to do
except fight, and they've not only included
victory conditions but also only included ones which require conquest. Warscore works for their games in general because they're very clearly about the historical deviation and interactions with other states, and are backed up by more robust systems for both war and peace, as well as a lack of war-oriented victory conditions. Stellaris just doesn't have... any of that, really.
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For reference, when I talk about keeping my distance from FEs before I can take them, this is what I mean:
Those pink Uriy assholes are xenophobic isolationists trying to claim-jump me in a hyperspace-only game, so I cut around beneath them to block their growth. The orange are a Holy Guardian FE--that is, they're generally nice... fungi who are Fanatic Spiritualist and nothing else, who have a patronizing (i.e. about as good as it gets with FEs) attitude towards me and +80 relations despite the fact that I've got -20 from being Fanatic Materialists and -10 from my purge policy.
Getting that close to their borders is still what I consider to be a pretty high risk move, only worthwhile because it will lock my primary enemy out from basically all coreward expansion, ensuring that when the time comes I'll be able to gobble up all the high-tech goodies on the Antina worlds, paving my way to get down to the FE in galactic south-west with the juicy ringworlds.
If they'd been militant isolationists I would never have founded a colony that close.
One thing you've really got to watch out for is researching Galactic Ambitions multiple times when you're close to a FE, since it's very easy to accidentally push your borders too close and start generating friction.
Another thing, notice how far back the fog of war is pushed? That's because I scouted the shit out of everywhere I could a long time before my colony ships started going out. I knew what was on the far rim of the galaxy before I founded any of the colonies I have that're even halfway towards the core. You don't have to survey every system when you enter it. Save one ship to survey, send one or two more out running as far as they can to fill in your starcharts before everyone blobs out.