Master of Orion II: Battle at Antares

fan patch version 1.50.21

Download 1.50.21
May 30, 2023   |   11562 kB zip file   |   installation instructions (txt)   |   changelog (txt)

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

12 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 system

Modding with plain text configuration files -- Lua scripting support -- Integrated mapgen functionality -- No special tools required.

mapgen parameters

Package Contents

We took great care putting together this installation package. It includes the patch, several mods, extensive documentation and MOO2 Launcher.

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)

MOO2 Launcher

Included with the download is MOO2 Launcher, a GUI program for easy installing, configuring and running the patch. Auto-detects GoG and Steam installations.


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, we do advise to carefully read the installation instructions before starting your adventure.

installation instructions (txt)

About us

We started development of the 1.50 fan patch in 2015, and released the first version (1.50.0) on February 6, 2016. The height of activity was during 2016-2019 but we still update the patch from time to time.

Microprose Patches

Master of Orion II: Battle at Antares version 1.1 was released on cd-rom in North American retail on November 22, 1996. Three days later the first patch, version 1.2, was released to the web. This patch for the NA release was distributed as a patcher program that would patch six version 1.1 files. The 1.2 download below includes that original patcher program as well as the six patched files. Version 1.2 was the basis for the EU cd-rom release mid December 1996. With patch version 1.3 came the cd-rom release of the German translation of the game. English and German 1.31 patches were released on April 11, 1997. With patch version 1.31 came the release of the French translation of the game. A Spanish+Italian cd-rom was released in May, containing an integrated executable (2-in-1) that contained a few undocumented bug fixes but still carried the same version number 1.31. At the end of 1997, the game was reissued under Microprose's PowerPlus brand. This cd-rom contained a 5-in-1 multilingual exe, again as a version 1.31, bringing the undocumented bug fixes to the other three languages, but this last official version was never released as a patch.

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 patcher program + patched files. 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, no Orion system on the map and modded race picks.

Designed for single player games / multiplayer with AI. ICE makes the AI much more challenging, changes race picks extensively and also brings a moddeed Tech Tree. The sole 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 VDC_X11_V68_B3-GM3. In the 'NR' version tech breakthroughs only happen at 100% each time!

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.

Melee mod
This experimental mod does away with all economy, and is designed for pure 2-player tactical combat. The map has only 4 systems: Orion, 2 home systems, and a neutral system. Each player builds 30 command points worth of ships. Both players send their fleet to the neutral system and duke it out!

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 can crash multiplayer games sometimes but works fine in single player games. Place the file in 150\scripts\main\ (no need to restart).


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.

a b d e g h k m m p s s t