Master of Orion II: Battle at Antares

fan patch version 1.50.20

Download 1.50.20
Oct 25, 2022   |   11567 kB zip file

This website is home to the 1.50 fan patch for Master of Orion II: Battle at Antares (Master of Orion 2, MOO2), a turn-based strategy game set in space from 1996.

About 1.50

The 1.50 patch fixes a slew of issues that remained in the game after the last official patch, version 1.31 from 1997, and the 1.40 fan patch from 2006.

Bug Fixes

10 critical crash bugs -- 8 networked multiplayer bugs -- About 30 interface bugs -- Over 100 game-rule bugs.

New Features

Random number of opponents -- 6th ship design slot -- Auto-designed ships -- Greatly improved build queue management -- Unbuy function -- New hotkeys.


Modding with plain text configuration files -- Lua scripting support -- Integrated mapgen functionality.

mapgen parameters

Included Mods

1.50 improved -- 1.50 multiplayer -- Version 1.2 mod -- ICE -- VDC -- Melee -- Randomized tech tree -- Lots of mapmods -- Mirror maps option -- A standard mode is available, which is only the patch, no mods.


The changelog describes changes for each version of the 1.50 patch. The manual has detailed descriptions of fixes, new features, modding options and game mechanics.

Changelog (txt)   |   Manual (pdf)


Supports English, German, French, Spanish and Italian DOS editions of MOO2. -- Installing 1.50 does not break 1.31 or 1.40 installations. Original files are preserved.


A working copy of MOO2 DOS version 1.31 or higher -- The MOO2 game directory should contain ALL game files (full installation).


While installation with MOO2 Launcher should be easy, it is advised to carefully read the installation instructions before starting your adventure.

installation instructions (txt)

MOO2 Patches

Fan patches

1.50.20 Multilingual
Fan patch. Oct 25, 2022. 11567 kB zip file
Development of the 1.50 fan patch for Master of Orion II: Battle at Antares (MOO2) started in 2015, and the first version (1.50.0) was released February 6, 2016. Now, seven years on, we have arrived at patch version 1.50.20. The Changelog (txt) describes changes for each version of the 1.50 patch. The download is a zip file that includes the patch, several mods and MOO2 Launcher. MOO2 Launcher is a GUI program for installing, configuring and running the patch. We took great care putting together this pack. If you encounter any bugs, do let us know on the MOO2 Discord server. You may also write on one of the forums that have a 1.50 patch thread. It helps a lot if your description is detailed, includes your ORION2.LOG, and a savegame from the turn before the bug happens if possible. Carefully read the installation instructions (txt) before installing the patch.

1.40b25f English
Fan patch. September 12, 2022. 1178 kB zip file
For 1.40 speedruns. 'f' stands for: Super fast screen switches and Build queue warnings disabled. The zip file includes a changelog (txt) and the source code of the 1.40 patch.

1.40b23 English
Fan patch. May 22, 2006. 30 kB zip file
The English DOS version sold online today is this fan patch from May 2006. The zip file includes the original patcher program that updates version 1.31 to 1.40b23, the readme and the changelog.

Official Microprose patches

Version 1.31 is required for installing 1.40 and 1.50 patches. There are no official patches for the French, Spanish and Italian editions because they were already at version 1.31 at initial release. The German edition released at version 1.3. English version 1.2 patch for the US version 1.1 cd-rom was distributed as a patcher program that would patch six version 1.1 files. The download below includes that original patcher program as well as the six patched files.

1.31 English
Microprose patch. April 11, 1997. 3350 kB zip file

1.31 German
Microprose patch. April 11, 1997. 2342 kB zip file

1.3 English
Microprose patch. March 3, 1997. 3294 kB zip file

1.2 English
Microprose patch. November 25, 1996. 4425 kB zip file


MOO2 Mods

Included with the 1.50 patch

1.50 improved
Proposes gently tweaked race pick valuation. Introduces new combat mechanics like Ship Initiative 2.0, Interactive Combat Stats (ICS) and Simplified Beam Formula. Makes various tweaks to weapons and special systems. Special care was given to improve AI ship designs. The Excel manual included with the download explains it all.

1.50 multiplayer
Based on 1.50 improved with a number of options for multiplayer enabled and modded race picks.

Version 1.2 mod
This little mod approximates MOO2 version 1.2 as close as possible with current 1.50 config: Creative costs 6 picks again, Psilon race design restored, original Guardian and Antaran ship designs, Plasma Cannon, Ion Cannon and Gyro Destabilizer weapon stats set back to original values.

Designed for single player games, making the AI much more challenging. This mod changes race picks extensively. The Tech Tree has also been modded. The only difference between ICE and ICE-X is AI strength: ICE-X Impossible has the strongest AI, you'd better know what you are doing!

This mod is designed for 1v1 multiplayer. Included is version X9_V66_B11_GM3.

Separate downloads

Spiral galaxy mod 1.0
Mod by Epirasque that creates a spiral galaxy, one arm per player with their home world at the tip.

Techtree mods 1.0 for version 1.50.19+
Bundle of Lua mods by Epirasque. Contains several mods that alter the research tech tree or otherwise interact with how players acquire tech through research. Follow the installation instructions from the included Readme. Note that these mods do not work on and earlier versions.

Miniaturization report for version 1.50.19+
Lua script that shows miniaturization report when you press '4' in the Main screen, which is useful with random tech trees. Script from patch 1.50.19 that is no longer included because it can crash multiplayer games sometimes. Works just fine in single player games. Place the file in 150\scripts\main\ (no need to restart).

No AI surrender mod
Micromod that prevents AI from surrendering before turn 1000. Unzip the No AI surrender mod and place the config file in 150\mods\150\, then restart MOO2 Launcher.

VDC_X10_V67_B7 for version 1.50.19+
Latest version of the VDC mod. See included readme for the changelog.


MOO2 Tools

Corion2 1.1.1
Savegame Editor. Corion version 1.1.1 has been optimized for the 1.50 patch. 153 kB zip file.

MoO2 Workshop
LBX editor suite by Grig de Griz. Handles text, picture and font files. Includes a leader editor. 2713 kB zip file.

LBX graphics viewer by Marco. Easy scanning of contents of LBX files. 20377 kB zip file. Other work by the same author can be found on Github.

O2M 4.02 page
Thread on CivFanatics for the modding tool and game launcher by Ponkyo. Includes a tech tree editor.
O2M is not fully compatible with MOO2 Launcher. If you want to use both, then create 2 separate MOO2 game directories, one for each launcher.

DOSBox website
Official website of DOSBox. Emulator to run MOO2 on modern machines.

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