Do any of you know of a game that has similar combat to MoO2, but one that focuses solely on the combat and ship design functions? Most similar games I find have real-time combat, and I'm specifically looking for turn based. Thanks for any suggestions!

Use the cheat codes to build some fleet by some rules (say 10000 RP from average start; 10 CP) and fight with other guy, who did the same. Get rid of economic entirely. Its quite rare, but working and not new version of moo2 multiplayer.

There are plenty of Boardgames, but I can't think of any computer games I've played that do ONLY turn-based space combat. There might be some early StarTrek title from the 80s/90s that would do that.

Oh! Yes, that reminds me. The obvious one that has a similar combat system to MoO2 is Star Trek: Birth of the Federation. It's another Microprose game, very much of the same mould as MoO2. I've been hoping it would become available here on GoG for a while now (my original disc got stolen). Unfortunately, its unavailability means that it's not really an option.

If you still want a bit of economy/management in the game, you might want to look at the Galactic Civilizations series. You can get the ultimate version of the first game here on GoG and on Steam, and there you can get the second installment as well.

If you only want space combat, I guess the closest thing I can think of now is Gratuitous Space Battles - which is probably a bit more like tower defense than what you're looking for, but it might suffice. You can find that on Steam as well.

I bought GSB years ago when it first came out, and it should more properly be called a fancy screensaver. There is literally no point other than lining up two rows of ships and watching them blow each other up. After about 30 minutes of that it looses its sparkle real fast.

There is also Weird Worlds Return to Infinite Space, by Digital Eel, which has a bare-bones exploration theme tacked on to a simple but fun space combat mechanic. You can build up a fleet of up to 5 ships, but you need to "find" the hulls and weapon systems during your explorations. The battles are in real time, but have a pause function so you can issue more complicated targeting and maneuver orders to your ships. The game is randomized so you never really know what you are going to end up with, but the weapon systems are quite diverse, as are the hull types, so there is lots of fun experimentation and cool weapon effects shown graphically during space battles. The game has a demo, so you can try it out. A full game usually takes about 30 minutes to play through, most times with your 5-year "mission to explore" ending in failure. The full game has an easter-egg space dreadnought you can sometimes find, as well as an epic boss battle that you can encounter if you have found the right tech and event combos. Oh yeah, it also has a Gratuitous Space Battles-like combat simulator where you can pit two or more user-defined fleets against each other. Watch the video here

A 4x empire-building game that nonetheless concentrates almost entirely on spaceship design is Sword of the Stars series by Kerberos. Check it out here (omg the soundtrack sucks for that video). Both the starmap and the battles are in 3D (strategic is turn-based with battles in real-time) but once again use a pause-function if you want so as to issue orders. That one is REAL fun, because you can see the enemy gun turrets swivelling and tracking their targets, and you can target your own guns to blow up individual gun turrets or the engines or the bridge, issue firing orders at multiple targets, whatever. Zoom out for an overview of the battle, or zoom in to watch the cinemagraphic laser barrage.There is a large tech tree that needs to be researched, and you custom design each ship you build using whatever weapons and defense systems you have available. Many hours of fun packed in this game.

Something that could probably fit in there ist Star General from SSI. Very old game like Panzer General in space. You don't have the ship design, but it mostly focuses on combat with your units.

You might also want to check out Imperium Galactica 2. I haven't actually played it yet, but I've been watching it on Youtube let's play videos. It looks very similar to the Master of Orion games.

It's not exactly what you're asking for, but you might want to give Faster Than Light a try (and, as already mentioned, SotS1 - avoid SotS2 unless you're really an hardcore 4X player).

Both focus on real time combat, but can also be paused any time you'd like to give orders (only in SP for SotS1).

On the other hand, if you want turn based combat, and design, I can only recommend Missionforce : Cyberstorm :
https://www.youtube.com/watch?v=B4MwrUCLnOc

It's not ships in space, but mechs on planets, but the combat feels pretty similar to MoO2!

Recently released 4X game Horizon attempts to recreate the Moo2 atmosphere (including turnbased, detailed combat), though reviews are rather mediocre (which I personally don't understand - and the game is still receiving updates to make it better)