Master of Orion is a good, but flawed game. Fortunately, we have mods to fix most of the flaws. This guide will introduce you to a few of the most popular ones among the community these days.

To begin, there's three places to get MoO mods: the Steam workshop, Nexus mods[www.nexusmods.com], and ModDB. There are more mods available on Steam, and they are easier to install, so if you have the Steam version, sticking to the workshop is typically best. If you bought the GoG version of the game, Nexus and ModDB are your only options. One significant difference between the Steam and Nexus/ModDB versions is that the Steam one will update your mods automatically when the author updates them, which on the one hand keeps your mods up to date but on the other hand can break save files for games you have in progress, so keep that in mind.

For Steam workshop mods, they are almost all installed the same way, with UCP (see below) being an important exception. On the mod page, just click the Subscribe button.

For Nexus mods or for mods you create yourself, you have to move the mod folder to Documents\Master of Orion\Mods. That's assuming you're on Windows; there should be a similar folder somewhere for the Mac and Linux versions.

Your mods should then show up in the mods menu the next time you launch the game.

The order of the mods on this menu is important. Mods are loaded top to bottom, meaning if two mods change the same setting, the lower mod on the list takes priority. You can change the load order by mousing over a mod and clicking the arrows that appear to the left.

Full disclosure: I am the author of many of the mods in this guide such as 5X, and so I am biased in my mod recommendations. I wrote this guide because there wasn't any other guide on getting started with mods, and I see questions about it on the forums all the time. I encourage you to browse the workshop yourself to see what interests you besides what I list here.

Master of Orion is a good, but rather buggy game. For example, eccm and fast missiles don't work at all, and MIRV missiles can't be hit by point defense weapons. Half of the ship modules are broken too, and there's a myriad of other bugs large and small. Fortunately, WhatIsSol has created an unofficial patch for the game that not only fixes most of the bugs, but it adds new UI features like rally points and custom auto build queues, AI improvements, and modding options too among others.
https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1109736522
Note: To make the patch work, you have to do more than just subscribe. This is because the code changes UCP makes are not possible within the normal modding framework of the game.You can find instructions on the UCP description, or follow my steps which include getting it to work with 5X:

1. UCP uses a Java installer, so you need to install JRE[java.com] if you have not already done so at some point.
   
2. Subscribe to UCP on the Steam page.
   
3. Locate UCP on your computer. From your Steam install folder which by default is in Program Files (x86), navigate to steamapps\workshop\content\298050\1109736522
   
4. Extract UnofficialCodePatch-Release.zip to a separate folder (it's important you don't extract it to the same folder as the zip is in)
   
5. With MoO not running, run javaInstaller.bat and select the install option. You should see it copy a bunch of files, after which it'll say Operation Completed Successfully and you can close the program. UCP is now installed.
   
6. Run MoO. You should see the UCP version number in the top right of the main menu with the game version; if so this confirms UCP is installed correctly. Open the Mods menu. You should see UCP and UCP steam workshop.
   It doesn't matter where UCP Steam workshop goes in the load order or whether it's active. You have to re-run the installer any time UCP updates.

The UCP readme has instructions for non Windows/Steam as well.

This mod makes quite a lot of changes to the game, but it really doesn't alter the vanilla experience intended by the developers. It makes no adjustment's to the game's balance, and so it is strictly an improvement over the vanilla game. I recommend it for all players, and I believe it's the single most essential mod to play this game.

If you have UCP installed correctly, the UCP version should show up on the top right of the main menu.


You should also see a new Local mod in the mods menu called Unofficial Code Patch. Steam users note, the workshop "Unofficial Code Patch Steam Workshop" mod is only a way of delivering the patch files, and it doesn't matter whether it's active or not or where it goes in your mod order.

The local Unofficial Code Patch mod needs to be active and should go above all other mods you use except if you use 5X (more on that below). Note that without UCP installed, your load order is reset every time a mod updates or you add a new one. The first time you install UCP, the load order will reset again, but after that it will no longer reset.

For more information on UCP's major features and how to use them, start with sections 2 and 3 of the Readme file[file-metadata.nexusmods.com].

Master of Orion is a good, but unbalanced game. For example, you may have noticed that the Meklar always win, and if you total up the custom race trait cost of their race and other races, they're all totally uneven. So back in Early Access, I decided to make some mods to fix it. Then I got a bit carried away and started adding new features and enhancements too, and I ended up with this giant overhaul mod called 5X.
https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=800155077
Besides rebalancing everything, there's new technologies, new game setup options, AI improvements, new custom race options, and just about every other feature I could squeeze out of the game's modding system. It is the largest (besides UCP) and most subscribed to mod on the workshop and practically a DLC expansion for the game. For a slightly less incomplete list of features, see the readme[file-metadata.nexusmods.com].

However, in order to get a sense of the game, I'd recommend playing without 5X for your first game. If you want to just try a less extensive version first, there's also the 5X Lite mod.

https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1146667764
I would recommend trying the full 5X after you've gotten used to the game.

Note: 5X is designed to run without UCP. In order to use 5X with UCP, you need to also get the 5X UCP Compatibility mod (5XCPC).
https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1190572281
This mod allows 5X to take advantage of UCP features and corrects for modding overwrites made by the local UCP mod. Most importantly, you must have the right load order. When using 5X with UCP, your load order should be

• 5X - The Ultimate Balance Mod
  
• Unofficial Code Patch
  
• 5X UCP Compatibility Mod (5XCPC)

I still update 5X from time to time to add new features and tweak the balance. I always give advanced notice before I do so that you may finish your games in progress before the update, as updating 5X occasionally breaks saved games and there's no way to prevent Steam from automatically delivering the update. Most updates this is not an issue, but I give notice just in case. You can always get previous versions of the mod on Nexus mods to finish the game you had in progress if this happens.

Another popular mod these days, though I don't always use it, is Diverse Specials and Massive Planets (or DSMP) by Morpheus. This mod adds over 100 different planetary specials that planets can randomly be generated with along with techs that can only be built on worlds with those resources. It also adds massive planets, which is a size above huge. There are several versions available: some for use with 5X and some for use without, and some with or without certain features. You can choose the version you prefer according to which features you want and whether you're using 5X:

• Full version without 5X: https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1120222144
  
• Full version with 5X: https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1199902121
  
• Specials only (no massive planets) without 5X: https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1811341802
  
• Specials only (no massive planets) with 5X: https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1246879078
  
• No added techs with 5X: https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1805523534
  
• Specials only with no added techs with 5X: https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1805510569

You should use only one version at a time, and if you are going to use it with 5X, the order of your mods in game should be
5X
UCP
DSMP
5XCPC
All other mods

There are a couple of extensions to the 5X mod that can further enhance your game.

First up is a custom assets package that WhatIsSol, Morpheus, and I created for 5X and DSMP.
https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1348895422
Note: The install process for this mod is similar to UCP, where you have to locate and run a java installer. Follow the instructions carefully.

It includes various icons and thumbnails for things added in 5X and DSMP. It can be used with 5X alone, with DSMP alone, or with both. It makes no gameplay changes, just visual enhancements, so this mod is very much optional, but I would recommend it to anyone running either mod.

If you're a MoO2 veteran like me, you might be missing the 8 distinct tech branches that the tree used to have. That's why I created a 5X add-on that re-arranges the entire tech tree into 8 branches.
https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=867373732
Recombining the tech tree in this way creates a ton of interesting new choices and strategies. It's not so much an improvement to the tech progression as it is an interesting alternative variation. I'd recommend trying this for players who have gotten used to the regular 5X tech tree and want to change it up a bit.

Vaaish has created an overhaul of the battle system in 5X. While 5X's combat can be seen as a re-balancing and enhancement of the vanilla system, Tactical Mod aims to create a new more interesting and dynamic experience through its overhaul of weapon and ship balance. I would recommend trying it after you've gotten used to 5X. It is compatible with DSMP and STT.
https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1687155720

The above 3 mods and DSMP can be loaded in any order as long as they're below 5X, UCP, and 5XCPC.

There's tons of other mods in the workshop. Most of them are simple, and some of them are compatible with 5X. Many of them do things 5X already does, like adding a volcanic transformation technology or making base defenses stronger, so they are redundant if you do use 5X. All of the other mods I've created are compatible with 5X unless it says otherwise on the mod page; just make sure to load them below 5X, UCP, and 5XCPC. Personally I tend to mostly run games with just the mods I've listed in the previous sections.

One popular mod is ALL AI originally by Dazgrum which lets you play up to 14 races (13 opponents) in a game (if you have all the DLC races, otherwise the cap is however many races you have and the game will soft-lock if you try to use more), though it does cause some bugs particularly with Antarans. That mod isn't compatible with 5X, but I created a version which works with or without 5X, and if you run it without 5X, it also adds many galaxy generation features like new galaxy types, ages, and densities and such that you would find in 5X. As an add-on to 5X, the only thing it does is allow you to play with 14 races.

https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1179207859
If you use it and play with more than 9 races, I recommend you play with Antaran attacks disabled, either by disabling the victory condition or using the first of the mods below.

There's a number of cheat mods for MoO, if you're into that sort of thing. The most popular ones I've made are these:
https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=863756867
https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=860669097
https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1134161249
https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=1380145079

I'm happy to answer any mod questions. If you're interested in creating your own mods, I have a guide to get you started.
https://steamproxy-script.pipiskins.com/sharedfiles/filedetails/?id=772694134

Didn't read any of that? Do this:

1. Install UCP right away. Follow the install instructions carefully!
   
2. Try 5X after you've gotten used to the game to see if you like it. Use 5XCPC to make it work with UCP. Load in this order in the in game Mods menu: 5X, UCP, 5XCPC
   
3. Skim over the links in this guide later for more good mods.