One thing I find odd about the Space 4x genre is that it remains popular and new games or expansions for existing ones come out fairly regularly but there hasn't been a genuine hit in it, seemingly since MOO II or so.
DW:U is the only 4x game that I would unequivocally say is as good as the original MOO2.
It's a bit niche next to Civilization, or Battle-Royale-FPS-of-the-week, but it's not quite at the level of flight simulators.
It does a lot to capture the magic of exploring space as a growing empire, especially through the special encounters and branching scenarios which go to some pretty wild places. I also love the huge variety of gameplay experiences offered depending on the attributes of the species you choose to play as.
Master of Orion, if I am being honest, feels like it has had much greater legs as a piece of abandonware and through re-release than it ever did in the initial run. I never even heard of it until many years later, when I found homeoftheunderdogs and abandonia because my computer was too old for what was then available in the bargain bin at Walmart.
A 4x game on land automatically has to represent terrain. That immediately brings our intuitive associations to the fore: mountains are impassable, hills are good for mining and defense, and you need ships to cross water.
A 4x game "in space" has to do without native terrain, and certainly without terrain that is automatically intuitive. The Plasma Storm Nebula is a creation (or not) out of whole cloth, with no natural rules beyond what the game designers impart.
That's a more complicated design space, and at the same time it's not immediately, emotionally engaging for the player in the same way that playing on Earth is.
But today we can have much deeper, more detailed world models. CK2 is awesome because it populates a simple civ-world of obtainable and upgradeable cities with thousands of simulated courtiers to meaningfully interact with, EU4 because it so carefully maps out all the socioeconomic forces that shaped the world when political interactions first started to become truly global.
If you add similar details to a sci-fi setting it just feels arbitrarily burdensome. There's no way you could connect with, say of a dozen of fungoid admirals in the way you connect with a Hanoverian Capet general who learned to respect eastern religions on an aborted crusade and is now wed to a close relative of a recently ousted Czar. A similar amount of details added to a generic space alien would have zero upside, you could just as well name the stats A through Z.
The rare exception was Alpha Centauri whose designer apparently understood that problem and focused on world building content instead of trying to out-4X all earlier 4Xs.
What I could imagine to also work in a generic 4X space setting is a game that makes ship designs the main characters in the spotlight: don't just have that customary complex ship editor, give the individual designs an identity by accumulating RPG-like bonuses over time so that an outdated but properly "leveled-up" design can remain a viable option over more modern contenders. You might want to keep those space-B52s flying when generations of experience make the damage control teams so much more effective, production lines run at 10x efficiency and all your modern gun batteries have been tailored to the confines of its surprisingly versatile weapons bay anyways. SMAC already had prototype cost, but that was seriously lacking flavor. Stellaris has the occasional event driven per ship bonus (iirc?) but that's too micro to be engaging. Blueprints for a series of ships could be just the right level of granularity.
Which is where the licenses tie-in, less as officially sanctioned and more as popular user mods! Set your 4X in the world of Dune! Or of Warhammer 40,000! Star Wars, Trek, Battlestar Galactica! Babylon Five! And so forth.
> give the individual designs an identity by accumulating RPG-like bonuses over time so that an outdated but properly "leveled-up" design can remain a viable option over more modern contenders
I'm pretty sure everything from the recent Civs back to the original Starcraft tracked unit advancement. But usually it doesn't translate to RPG levels of immersion. I think Starships Unlimited, an early 2000s indie space 4X, did this fairly well.
Most of those depict a single conflict, hardly a match for the 4X playbook.
> I'm pretty sure everything from the recent Civs back to the original Starcraft tracked unit advancement.
And in some of the Civs (4 or 5) it was so powerful that some of the modern units were comparatively worthless unless they had "skills" that they could only get by inheritance on the individual unit upgrade path. You'd have a clear separation between core units nurtured through the ages all the way from antiquity and gunfodder whose job was to keep the core units alive. That was all rule-gamey and zero flavor. Also too micro in my opinion and single units are still not important enough to be considered protagonists of the story.
Space 4X already come with a ship designer ever since the original MOO. But it's often just busywork to illustrate the tech progress a little. I think that this is a place that could be extended without feeling pointlessly micro or suffer from faceless genericity, if done right: so research has discovered positron phaser torpedo projectors (aka random generic technobabble). The technology apparently has an efficiency sweet spot at 50m bore length. Should the development branch design a new hull around those dimensions or do we create a less efficient module that fits our venerable, cheap Bounty-class frigate that gives crews +10 morale because of that popular holovid show set aboard the lead ship of the class? (aka random flavor event hull class bonus). And all the specialty role ships that have been derived from that hull? It would be an interesting game mechanic because you can't fall into a default pattern like "always go for the biggest, longest range weapons and avoid battles where the enemy might come into close range": even the most module-conservative player would occasionally have to cut compatibility introduce a fully new generation. An echo chamber, where the player is mostly interacting with consequences of her own decisions. Decisions that are not necessarily better or worse in terms of running but that are meaningful because they shape your future options. That's what I expect from all games that aren't just about eye candy or reaction time. I like the idea better the more I think about it.
This could actually be a very nice Stellaris DLC, a boatload of chance event microcontent and a total overhaul of a game mechanic that can be rewritten in total isolation of the others. If only Paradox were into making DLC! (just kidding there of course)
Hasn't really hurt Battletech over 35 years of endless game releases over various media. But that's not a 4x setting, and neither is Starcraft. In my happy Moo2 treats, the duo of unit design and turn based tactical battles was the one thing that made anything relatable, the tech tree in this case.