I didn’t react to your comment but I disagree with it because I think it’s too simplistic and enacting it would be dev time better spent elsewhere. Sounds like your main issue is you want the technology of cosmogenesis with the aggression of nemesis, in which case you can get that by playing a genocidal empire and picking cosmo. Trying to fit all crisis events and systems in one will likely make a mess.
I’d argue that this basically already happened in miniature already. Galactic nemesis is, IMO, poorly done. It tried to be too many things at once and tonally is a mess. There’s no sensible link between menace points and the unlocks you get from them (how does genociding lots result in the technology for mineral corvettes or star killers?), whereas advanced logic and the means to get them completely fit the cosmogenesis path. Also aesthetically nemesis is trying to be both an ork Waaagh! where swarms of low-tech scrap ships are thrown at enemies and incorporate eldritch hypertech evocative of intellects vast, cool, and unsympathetic.
If the devs tried to combine the two I feel we’d have even more of a thematic mess where the flaws of nemesis undermine the polish and coherency of cosmogenesis. If anything I feel we should have the opposite to all-in-one. Instead nemesis should be broken into two different crises, one thematically appropriate for an empire that Waaagh!s with scrap ships and one that focuses on eldritch hyper tech. But I wouldn’t say that this should be any sort of priority, since there are better things the devs could work on.
Not the "aggression" of Nemesis, just the existential threat the rest of the galaxy treats you as. I might have mentioned it in the original post, but I'm basically after stuff that allows me to more accurately roleplay the Reapers from Mass Effect. Also, if you just play as a genocidal empire and pick Cosmo, that won't have the same effect as picking Galactic Nemesis because unless they've recently changed it on PC (consoles have just gotten Galactic Paragons), no matter how powerful *and* aggressive/violent you are, empires will actually *STOP* declaring war on you because they know they'll lose. I have never once been declared a Galactic Crisis even hundreds of years past the End Game, but playing as a Galactic Nemesis makes it so that once you reach the final tier, for the rest of the game all empires are in open war against you until you are fully destroyed.
In the current system, this is kind of exploitable because there're no actual buffs or bonuses needed from the final Menace Tier, so you can hold off on the final research project that causes everyone to declare war on you until you've built up your power to satisfactory levels. I will say that I'm also not a fan of the "blip the universe out of existence with the press of a button" mechanic, but that's just me.
I've suggested it before (maybe not in this thread), that I'd love a Machine-based Crisis path that results in you building a Megastructure supercomputer that allows you to become a Singularity, and the each tier reduces Empire Sprawl by a total percentage, and the final tier eliminating it completely, allowing you to abuse your techs and traditions to your (my) hearts desire, and instead of just getting a victory screen, you still get to go around and destroy everyone normally if you want. Maybe as an extra caveat, when that Megastructure is completed, it presents the small threat that if the galaxy is able to destroy it in an attack, your entire empire is destroyed. Gone, boom, in an instant. I'll let you guess which 3rd game's final battle I've got in my head.
Also, just to be clear, when I suggested a "general" Crisis system that allows you to choose your path and perks, what I was suggesting was for the game to not choose your empire's "theme" for you and have you decide that yourself, choosing the buffs and perks that suit what you want. For example (we'd need more Aetherophasic Engine equivalents for this), if you picked Nemesis, you know you'd end up on the entire galaxy's bad side, but that doesn't have to mean you're - as you described - orks that throw thousands of cheap corvettes at their enemies. To use the Reapers from Mass Effect as the obvious example, they were largely indifferent to the morality, politics, societies and technologies of organic civilizations. All they cared about (as far as you could tell from the first two games) was increasing their own strength. It was the acquisition of strength for it's own sake.
To me, Cosmo has a similar problem you've described for GN, the only distinction is that it "makes sense" in-universe. My empire doesn't want to enter another universe and reshape reality from scratch Thanos-style, just like how in GN my empire doesn't have any interest in becoming Shroud Gods, which is why I never finish the Engine's last stage. Cosmo's "theme" is consistent with itself, which is a bonus over GN, but it still doesn't present the player with many roleplaying options. Even if I do what I do with GN and stop just before the end, it still would be kind of breaking the purpose of the perk.
I'm wondering if to try and solve your problem with GN and my problem with Cosmo it might be a good idea to change the Crisis Perks from turning your empire into another of a specific theme and "character", and instead take it back to when it was called Become The Crisis, but bake it into something similar to the Civic system, to use Determined Exterminator as an example. Your civics (or maybe ethics?) would decide what "Crisis-type" you are (again, we'd need more events for this to actually work since we only have two right now) and the Become The Crisis Perk would enable you to actually pursue your empire's "dark side" as it were, since it could actually be you want to play as the good guy for once and it'd be really annoying if you were somehow locked in at the game start, barring the obvious civics. After you take the BTC perk, you'd then start unlocking player-chosen bonuses with the available choices being based on your "Crisis-Type". If you're a Determined Exterminator or Fanatical Purifier with a hatred of organics (or aliens in general), you might not care so much about strength and superiority, just about eliminating potential threats, which would be similar to GN and would have thinks like the Menacing ships. And the reason I threw FP in there was because I'm not sure a FP would be patient enough to wait for advanced technologies as opposed to eliminating their enemies as soon as possible. Not sure what we'd have for Driven Assimilator, but if you avoided those civics and I just had a normal Machine Empire with no explicit motivation other than to simply take strength and add it to myself, the choices could be a mix of highly advanced technologies mixed with combat proficiency and expertise (like the FE Battleships/Titans and the 40% ship damage). To make this work, we would also need to do something with the AI's capability of declaring you a Crisis, assuming that hasn't already been done in between console's current build and PC's