OK, so, things have been quiet in the Niops thread lately, and after seeing the Marian thread recently talking about what designs the Hegemony should produce, I revisited the idea for Niops: if and when Niops rebuilds their local military hardware manufacturing, what should they look into building?
Because Niops' industry has been beaten down to almost nothing, I decided to exclusively look at two tech bases: Primitive and Intro tech. For the most part, I'm sticking to designs that Niops would either have likely have access to as a former Star League colony, or that are readily-available and common in the Periphery. I've also tried to find as much overlap with fusion engines as possible, to cut down on the number of production lines they'd need, and prefer to minimize the number of weapons types that need to be manufactured, maintained, and fed as well. I've also stuck exclusively to stock, canon designs
So, let's start with Intro Tech, shall we? We know, from canon, that Niops expressly produced three named designs: the Black Knight, the Highlander and the Burke.
The Burke gives us a 150-rating engine, but uses ferro fibrous armor, so it's actually outside my criteria. Should Niops continue to be able to produce its engines and PPCs, though, you can get the SPD-502 Spad, and that same engine could get you introtech Commandos like the COM-2D - according to the MUL, it's Periphery General in the early Republic era, so that's feasible. The FFL-4A Firefly, an intro tech version of an old Star League design, would be another possibility. The problem, of course, is there's almost no weapons commonality between the three designs.
The 270-rating engine opens up a few more doors. first, you can keep intro-tech Highlanders, like the HGN-733P, in production, and also get the intro tech Phoenix Hawk, Hussar, Tomahawk and Ahab available to you. I could not, however, find any intro tech vehicles that used the 270 standard fusion, and the AHB-X and Highlander also use a crapload of different weapons. There is good overlap between the PXH-1 Phoenix Hawk and THK-33 Tomahawk, though, as well as with the HSR-300-D Hussar.
The 300 Vlar opens up huge numbers of doors. You've got two intro-tech versions of the Black Knight (one with a PPC, LLs, MLs, and an SL, and the other with just LLs, MLs and SLs), the Marauder, the Orion, Atlas, intro-tech Mackie, intro-tech King Crab, intro-tech Champion, the Ostsol, the Chameleon, the Eagle, the Stuka, the Thunderbird and, for a tank, the Merkava Mk VIII. If you've got the 300-rating engine, you're golden for frontline combatants.
Another one I looked into was the Vlar 160, which is used by the AM-PRM-SH1 Space Hound ProspectorMech, something I could see Niops and Interstellar Expeditions working together to build a production line for to aid in mining asteroids for germanium. It's only got a single small laser, but the Vlar 160 was also used on the Whitworth, Locust and intro-tech Mercury. The Locust and Mercury both have all-energy configs, which would cut down on logistics, too.
With the 300, the 270 and the 160, your best bet would probably be to build the following:
MCY-98 Mercury
Space Hound
PXH-1 Phoenix Hawk
BL-7-KNT Black Knight
Merkava Mk VIII tank
HGN-733P Highlander
Eagle ASF
AHB-X Ahab ASF
That puts your recon and your industrial 'Mech using one engine, your medium strike 'Mech, mainline BattleMech and main battle tank using another, and assault 'Mech and anti-ship ASF using the third. It also gives you redundancy should there be an issue with one of those engine production lines. There's overlap between the weapons production, too. If you can't produce one of the three engines, you've got other solid options, as well.
Now, here's the tricky part: what if they're stuck at a Primitive tech base for a while?
If that's the case, you're going to want to have as much overlap as possible, again, but this time you're starting from scratch. Worse, exactly one of your old engines, the 270-rating, is used by a primitive design (the primitive EGL-R1 Eagle). Ideally, assuming you'll be able to use these same fusion engines later down the road for intro or standard tech designs (see my rules board question), you'll not only want to maximize the number of designs you can use now, but also want to maximize your upgrade paths. Vehicles, if you're this bad off, are probably going to be based on older primitive support vehicle tech, which don't use the same engines, sadly.
This, in the end, boils down into five engines: the 180-rating, the 220-rating, the 240-rating, the 255-rating and the 360-rating.
With the 180-rating, out the door, you could build the primitive Lightning and Helepolis, which gives you a useful aerospace fighter and an artillery 'Mech. Your upgrade path to intro tech gains you 'Mechs like the Javelin and Blackjack, but also the intro-tech Wyvern and, when you eventually get back to your original tech base, the SLDF Wyvern and Galahad. I've not, though, been able to find any intro-tech fighters or vehicles that use this engine.
The 220-rating may seem odd at first, but it gives you the original Kyudo, the Star Dagger ASF, and the primitive Centurion ASF. Your upgrade paths here are weird: you end up replacing the Star Dagger or Centurion ASF with the SB-27 Sabre, and gain the ability to produce the intro-tech versions of the Prowler explorer vehicle, a unit that was highly popular with Explorer Corps, and one that Interstellar Expeditions might like, but which could also double as a decent infantry carrier for the Militia.
The 240-rating engine is, of course, a popular engine at the intro-tech level. For primitive tech, it may only get you the SHD-1R Shadow Hawk and RFL-1N Rifleman, but moving up to intro tech your upgrade path gets you the RFL-3N and RFL-3C Rifleman, the various intro-tech Merlins, the intro-tech Lancelot, and the F-90 Stingray.
The 255-rating gives you an interesting starting point: the retrotech SPR-DH Sparrowhawk, with its MLs and ERSLs, and the ancient BKX-1X Battleaxe, with its large lasers, LRM-5s and SRM-6. When you finally get an intro tech base back, you also get the Stalker, which everyone loves, the dumbed-down Crockett, the Longbow 7Q, and two useful vehicles once you can produce standard/Star League tech: the Thor and the Glory.
Lastly, there's the 360-rating engine. This, of course, gives you the prototype Mackie 5S with its PPC, LL and AC/5, the production Mackie 6S with its PPC, twin MLs and AC/10, and, importantly, the primitive HMR-HA Hammerhead with its twin MLs. Upgrading from here, though, is weird, because the only thing I could find that uses the same engine was the Cyclops - a decent enough 'Mech, but still kind of limiting.
If you're stuck at this level, then you should probably stick to two engines, at which point I'd say your best bet is to either do the 220 or the 240, and the 255 or the 360, depending on which plans you can get.
The 220-rating and 240-rating are both pretty safe options, since the primitive Kyudo, Star Dagger, Shadow Hawk and Rifleman were all Terran Hegemony designs, as was the Prowler. You're probably going to be able to get the Sabre, too, without much difficulty. The Shadow Hawk or Kyudo would give you a solid trooper, as well.
The 255-rating is tricky: both primitive designs that use this engine are foreign, and may be hard to get ahold of. With the 360-rating, though, you've got two solid Terran Hegemony primitive designs, which would serve well in the NAM: the primitive Hammerhead is quick enough and has solid enough armor to fulfill the role of general-purpose fighter, and the Mackie, despite being primitive, is a solid assault.
In the end, I'd probably say build production lines for the 240 and 360 fusion engines, then start building the following designs:
SHD-1R Shadow Hawk
RFL-1N Rifleman
MSK-5S Mackie
HMR-HA Hammerhead
That requires you to build the PPC, the large laser, the AC/5, and the medium laser. Your Mackie and Shadow Hawk share AC/5s, your Hammerhead, Rifleman and Mackie share large lasers, the Shadow Hawk and Rifleman share medium lasers, and the only odd duck out is the PPC on the Mackie, but you're still building only a limited number of 'Mechs, getting you a trooper, a fire support 'Mech, an assault 'Mech, and a general-purpose fighter, and your forces still have a distinct Star League feel, even if it's a retro one.
(I've attached the spreadsheet I used to work all this up, BTW.)