Old-school Freelancer player / modder here. I wrote an early steering-code experiment for a clone, but it never went anywhere. Pretty funny that this came out of similar things.
Played the Demo. Wow, this is super-ambitious for a one-person show! I'll probably buy it when it's out... but see the long, long list of rough edges (and this is what I found in less than an hour).
Areas That Could Be Improved:
1. The first mission is just plain confusing. A lot of it is the non-existent VO; reading text while trying to fly, etc., is a pain and frankly, I don't think it serves your game design well, other than cutting costs. Micheal King's dialog drives the first mission of Freelancer, providing the necessary exposition; you may want to record yourself giving the basics on that mission and just hope for the best; I'd rather hear the world's dorkiest Coder Voice than try and read text in the upper-left whilst trying to steer.
2. However, it gets worse, for that stuff. Cutscene text flies by so fast that most people won't be able to read it.
3. The graphics are... well, they're there. The lack of shadows, in a modern game on Unity, is a strange choice, and things felt muddy in places. The super-low-poly-everything and the low quality of the skins just kind of makes me wonder what was going on here; lack of time / budget, or will players eventually be able to mod it into something decent for 2023? Like, I don't think a game like this has to be amazing, in terms of production quality, but it feels retro-crude in an awkward way; Freelancer's graphics felt polished, but limited by the technology available. I'd seriously consider hiring an artist to re-skin the key assets (and I know a guy who'd probably shine).
4. The price to sell the newbie ship is far less than the money you get if you sell all the equipment on board. You can't sell the ship and transfer the equipment to storage, nor auto-strip it of equipment and transfer it to a new ship. I'm got briefly stuck, because I didn't have enough cash left to afford the shield on the new ship I just bought after the first mission. Thankfully, the info-courier missions are a cakewalk.
5. Combat felt off. The movement system felt OK, although some of the key choices were odd (shift+W to enter High Drive, in particular, felt clunky). Guns don't auto-converge like they did in Freelancer... and worse, the auto-lead indicator doesn't work properly (that involves solving a quadractic twice for XY / XZ axes to properly compute XYZ lead vs. target velocity; whatever you're doing, the results aren't terrifically accurate).
Weapons don't appear to have inaccuracy values, either. This sounds ok and I'm sure some of it's "in space, everything should be perfectly accurate", but from a game-design POV, it meant that less-accurate players could get "pretty close" and get hits at longer ranges. This also has implications that aren't great for the AI; one imagines that this means an accurate AI with high-level guns just auto-turrets players into scrap instantly, which isn't fun.
Shots felt like they were moving more slowly than FL, and enemy hitpoints after shields went down felt pretty low... at least with the basic fighters. There were some fighters in the first mission that were a totally different picture, in terms of how often they had to be hit just to knock shields down.
Overall, enemy ship AI was OK, but it never did the stunts that made Freelancer's AI interesting, and I noticed that it tended to fly into objects a lot. BTW, those were canned data, basically; a few seconds of forced yaw for a barrel-roll, a fairly explicit path for loops, etc.
6. The stats that players need, to decide which ships to pick up, aren't available. Freelancer had this problem to some extent, too, but in a modern game it's less excusable. Like, we need to know that a ship accelerates / turns better, or has great side-strafe; as it was, there weren't any obvious reasons to pick a lighter fighter over a heavier one, even though I'm sure that the lighter one probably turns better, etc. There's also a lot of what I'd call "junk data" left in those UIs, where it's showing stuff that's probably of interest to a developer, but not to a player., like the lists of abbreviated stuff a ship has. Frankly, your system's a lot more complex than FL's was, so making that UI clearer is pretty key.
7. The first place I docked, it took me two tries to find instant-action missions... and all of them were FedEx Quests; no combat. Same at the second and third location I've hit. One area where your game could clearly be better than Freelancer is having more variety to the combat missions; it only really had two variations.
8. The big enemy ships on the first mission aren't armed. They're just big targets that the player can barely damage. Is that on purpose? They felt superfluous, since only your wingmates with the purple beams could kill them easily.
9. Wingmates felt like they were barely there. They never got any kills except on the big slow-moving targets, and I hadn't made any emotional / plot connection with them, so I couldn't have cared if they were invulnerable or not.
10. What on Earth is with all the humans not having legs and wearing weird masks? Not sure what you were going for there, other than, "I don't wanna animate people walking", but I largely felt like they could've been replaced with a nice basic 2D representation or just a standing idle that was OK. IDK, the masks thing was just kind of creepy, their red eyes were creepy, and they all felt like clones. One of the things that made Freelancer work was that people were just ... people.
11. The whole backstory, which appears to imply that there's some sort of Cthlulu-esque Space Nasty out there as an Ultimate Threat, rather than Freelancer's rather messy aliens (which always felt like about half of the plot got left on the cutting-room floor when Microsoft made the decision to rescue the project after the epic failure of Chris Roberts resulted in a really rapid patch-and-fix job, and it's a wonder that it was as good as it was). That said... why am I fighting cultists, exactly? Like, I just did a whole bunch of, "uh, what?" about how things work, plot-wise. Do people worship the Space Evil? Why? Does it give out free candy?
12. Weapons have different shot-speeds and confusing pseudo-science terms that don't make it obvious what counters what, etc. Like, why not use "plasma", "laser", etc.? The pseudo-science gibberish always works better when it's hung w/ words that actually exist ("actuate the photon masts" sounds waaaaay better than, "gremulate the wee'don railles", even though both are silly).
Freelancer had this problem, too (weapon speeds and stat problems), but it mainly didn't matter to expert players (the fast-firing, fast-velocity weapons with the longest range were always best, for advanced pilots who turned on "advanced flight mode" and kited everything). While I haven't played the demo long enough to have a firm opinion on this, I suspect there are severe balance problems with the weapons, much like Freelancer had. In general... in a game where leading shots matters, having different velocities means the lead indicator needs to handle that very gracefully (multiple markers, for example) and low-velocity, low-range guns need to be much, much more potent (we're talking twice as powerful and up, depending on how hard they are to hit with and how slow they fire) than the other ones, or they will not get used, because DPS is irrelevant if the weapons just don't get into range much or miss a lot because of low fire-rates.
Frankly, I would've ditched the shield / damage "elemental" system and just made sure every weapon had a clear use-case and felt fun, but that's just me.
13. There are a bunch of neato features that seem like they're stretching into all the wish-list things FL players might have wanted, like the ship-customization system. That's great... if the underlying content is great. As it was, the low quality of the meshes and the shader employed lacking specular highlights, etc. didn't work for me. Honestly, when I see a feature like this, I just want to tell you to drop it and work on things that matter; this kind of thing would be a great follow-on after the game itself is great and it's a financial hit for you.
14. There are rendering issues. Planets appear to be rendering in a pass or mode where they're cutting off the signs and the red / green markers for the space lanes sometimes.
15. Combat noises are OK, but the ship itself is silent far too often; there isn't that ever-present white-noise that movies and games have been using to convey that you're in a massive, high-tech machine that's doing stuff.