It's loosely in the same genre but you may like Rebel Galaxy. It takes a slightly different approach to space combat making it closer to naval warfare. Very enjoyable soundtrack.

Not really what is looked for here in most ways, but there's Parkan.

I have little to say other than it exists.

Haven't seen anyone mention Starpoint Gemini. Warlords was probably the best iteration. Kinda like Eve but single player and a half way decent story.

Still in early access, and not very pleasant to looking at first glance, but Ostronauts is a start from scratch go anywhere and solve problems space game. On my first play I was pulled over but the cops for salvaging without a license only for the cop to write me a ticket and then start flirting with me. I got his number. Make sure you can cover the cost of the ticket and docking fees before you dock or they won't let you undock. Flight mechanics are very real and you quickly feel like your piloting a space jalopy. RPG system is great too. You unlock skills that level as you use them and need to repair components as they can break down. Slow development by I think one guy, but a work of love for sure.

I'm commenting late, but there is The Precursors which does require Slavjank tolerance, but if you have it, it provides an interesting flavor on a space opera adventure.

I also haven't tried The Tomorrow War which seemingly requires even higher Slavjank tolerance, and probably isn't a top of all time game, but seems interesting if you like peering into strange forgotten games. Warlockracy did a video of this one.

so for something completely different and focusing solely on the "size" aspect:

the biggest, that i am aware of, game in terms of sheer SIZE involved, is Stellaris:

it's a paradox grand strategy game, not first person at all, so completely different from the other recommendations and probably nothing to do with what you asked for...but if you want something truly MASSIVE...well...can't go much larger than galaxy spanning all out war involving gigantic fleets and armies!

so if power fantasies is something you're interested in, maybe take a look! it's pretty easy to get into, but has a lot of depth (but no requirement) to master later on! and it has a lot of settings regarding game speed and difficulty to tailor it to your tastes.

and mods, god help me, the mods; play a couple hours to get to know the game, then definitely get Gigastructural Engineering from the workshop. short list of ridiculous engineering:

• Attack Moons
• Behemoth Planetcraft
• Neutronstar Gigaforge
• Matryoshka Brain
• and a bunch, even more ridiculously huge projects!

(sidenote: the new DLC subscription on steam is...kinda worth it honestly. not the worst idea, especially to just try it out for a couple hours. i was extremely skeptical, but it's kinda, surprisingly, less predatory than the previous "we'll release 2 20$ DLCs, and 1 30/40$ DLC per year" model...)

If you're into retro-gaming, Starflight and Starflight II were both excellent.

https://en.m.wikipedia.org/wiki/Starflight

https://en.m.wikipedia.org/wiki/Starflight_2:_Trade_Routes_of_the_Cloud_Nebula