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OpenMW (also known by the abbreviation "OMW") is not actually a mod, but a freedom-respecting (GPL) implementation of a new game engine for The Elder Scrolls Ⅲ: Morrowind and associated file formats. The project was founded in 2008, releasing its first public version in June 2008.

Development is steadily approaching parity with TES3's Gamebryo engine, and players can adventure without undue difficulty or complications in the majority of cases. OpenMW already boasts features not in Bethesda's engine, including superior performance and stability. OpenMW also handles addon-heavy configurations better than Bethesda's engine.

OpenMW runs natively (without emulation or virtualisation) on POSIX (Unix-like) operating systems such as GNU+Linux and [Free|Open|Net]BSD (including Mac OS X), and MS Windows. It has been experimentally compiled for other platforms, including Android.

OpenMW is not a clone or reimplementation of Bethesda's game. Contrary to some assumptions, it does not include any of Bethesda's resources; rather, it is separate software for parsing the same data files, just like a modding tool. Compare using different image software to view the same image file.

OpenMW includes wizards to make installation and configuration easy and swift; configuration can be imported from an existing installation, and OpenMW can use an existing Data Files directory, or facilitates making a fresh installation of the game-world data, without Bethesda's bundled installer or its engine.

To play Morrowind, OpenMW requires a valid copy of the game-world data, such as from CD-ROM, GOG or Steam. It fully handles the Tribunal and Bloodmoon expansions, and the entire Game of the Year Edition.

Characters saved using Bethesda's engine may be imported (via conversion) to OpenMW's format, to allow one to continue playing pre-existing characters in OpenMW.


OpenMW fixes many problems of Bethesda's engine, enhances many features relating to functionality and gameplay, and adds features which are not present in Bethesda's engine.

Main article: OpenMW Wiki § Features

  • Stability and Integrity:
    • Including when heavily-modded and running at high-fidelity
    • Saving of character-state is now much more rigorous, avoiding various forms of corruption and other glitches
    • Elimination of artificial limit on count of mods+saves
  • Performance:
    • 64-bit builds for native execution; no more 32-bit compatibility modes
    • multithreaded; thus, can use multiple(-core) processors
    • Takes maximal advantage of modern GPUs; especially noticeable when the game is modded with higher-resolution textures and meshes
    • Uses OpenSceneGraph; tuning and optimisation refinement is an on-going effort although it already performs better than the original engine (and earlier releases of OpenMW which used Ogre3D)
  • Graphics:
    • Improved support for old(er) graphics hardware
    • More configuration options; allowing granular control of graphical fidelity, thus more tunable to the player's hardware and trade-off preferences
    • Arbitrary display resolutions in either full-screen or windowed modes
    • Rendering range (view distance) can be set much further than the original engine allowed
    • Anisotropic filtering
    • Adjustable field-of-view
    • New water shader featuring reflection and refraction rendering; highly realistic appearance
    • Enhanced shadow rendering; both fidelity and range
    • Improved rendering precision. The vanilla engine had precision issues that result in objects shaking when the player travels far from the world origin (co-ordinates: 0,0,0).
    • Support normal, specular, and parallax texture maps
    • Unclamped lighting
    • Improved sun flare (using occlusion queries)
    • Seamless terrain rendering, including distant terrain
    • Support for OSG mesh / scene files as an alternative to the proprietary NIF format
  • Data handling:
    • Character-state:
      • Saving is now much more rigorous, avoiding various forms of corruption and other glitches
      • Characters saved using Bethesda's engine may be imported (via conversion) to OpenMW's format, to allow one to continue playing existing characters in OpenMW
      • Saves are organized by character
      • Track the time played (optional toggle, not enabled by default)
    • Multiple data directories
  • GUI and usability:
    • GUI scaling option, useful to improve readability on high-resolution displays
    • World map adjusts automatically to fit new landmass from mods such as Tamriel Rebuilt
    • Save+load dialogues: saves are organized by character
    • Item selection dialogue now accepts manual typed input of an arbitrary count of items, in addition to the slider
    • alchemy dialogue: resizeable and redesigned
    • Allow keyboard input for item count dialogue and trade window price
    • Improved console (colours, tab completion of commands and object IDs)
    • Copy and paste from and to OS clipboard
    • Many sundry usability improvements
    • When placing items, irrelevant windows (stats, map, and spell windows) will become transparent on mouse-over and allow click-through
  • Input Controls:
    • Hardware game-controller support; currently with basic in-game configuration UI
    • Hardware cursors; this means the GUI cursor is always fluent, independent of the frame rate
    • Keyboard layout support — original Morrowind would always use QWERTY keyboard regardless of system setting; OpenMW will map commands to the same physical keys based on your configured keyboard layout
    • Held attacks (e.g. a nocked arrow) may be cancelled by using the Ready Weapon key
    • The "finish your current attack before equipping a new weapon" error has been removed and instead plays the weapon equip animation
  • Media:
  • Scripting:
    • Stricter compiler and compiler warnings. Error handling in the vanilla MW script compiler was very limited
    • Function arguments can now be expressions of arbitrary complexity. Vanilla MW would not even allow simple variable arguments for some functions
    • Arbitrary limitations on code depth/size are not present anymore. For example, there was a limit on how deep you can nest if/endif clauses. And there was also a limit on the length of a if/endif block
    • Script variable values are stored by name in saved games, so that reordering or adding new script variables in a content file does not cause incompatibilities with existing save files.
    • More hooks for mod-makers to employ.


OpenMW eliminates the need for some mods entirely; see the FAQs:

OMW is capable of running most mods that are well-implemented and which are not dependent on executable (.EXE, .DLL, or .COM) files that tamper with the engine's behaviour. Thus, OMW is not compatible with mods that rely on Morrowind Script Extender (MWSE or MSE), Morrowind Graphics Extender (MGE), Morrowind Code Patch (MCP), or their derivatives. Indeed, much of the inspiration for the project is implementing such capabilities natively into the game engine itself, rendering such hacks unnecessary. OMW is compatible with Morrowind Patch Project (MPP), and the OpenMW forum users recommend using it.

OpenMW is deliberately stricter when parsing scripts, and thus is far less forgiving of coding errors that the original engine. It will not compile mod scripts containing significant errors. This renders some old, sloppy mods incompatible sans suitable patching, but makes OMW much more stable; crashes are rare.

OMW reads .ESP, .ESM, and .BSA game data files, and introduces a libre plug-in file format, .omwaddon. The latter can be used for making patches (including of .ESP mods) or for creating all-new mods.

OpenMW introduces multiple data directories, so that mods' content files remain in their own directories and do not contaminate those of the original game, though players may also move files into the game's own Data Files directory, the same way one would mod Bethesda's original game engine.

Mod loading order in OMW is (re)configurable, and is not dependent on file hacks (e.g. faking the creation dates) as the original Bethesda engine necessitated (though that limitation has long been avoidable with third-party mod management applications). OMW has its own built-in mod manager for mods that are purely .omwaddon, or .ESP/.ESM; those that provide new resources in Data Files directories must have their load-orders managed in the configuration file.

The new game engine supports proper bumpmaps; while this makes for improved graphics over the original, it requires some mods that used "fake bumpmapping" to be patched to avoid excessively shiny textures (see OpenMW's forums for links to an easy tutorial for how to fix them).

Unlike Morrowind, OpenMW supports up to 18.5 quintillion (18,446,744,073,709,551,615) mods installed at any one time.

Additionally, the engine supports Full compatibility with all Morrowind mods (that do not rely on MWSE, executables, or exploiting engine bugs) is a stated goal of the OpenMW project. Consequently, its development team maintains close relationships (e.g. bug tracking between projects) with those of major mod and patching projects like Tamriel Rebuilt and MCP. The OpenMW Forum also hosts many play-testers' solutions to working around issues encountered with particular mods, and the community maintains a mod compatibility list.

Other differences[edit]

The engine is also progressively fixing the bugs and misfeatures of the original Bethesda engine which led to the development of MWSE and MCP. This may affect some known exploits in the vanilla game, though the project's goals are to replicate "stock" gameplay as much as is reasonable.

OMW's native graphical rendering effectively makes redundant the MGE project for the original game engine, but OpenMW makes it available cross-platform, and in a project that can continue to be developed (instead of being tied to a hard-coded executable dating to 2002, which will eventually become incompatible with future versions of operating systems).

OpenMW uses its own savegame format, but can import from Bethesda's using the bundled tool.

There are two experimental third-party leveled list merging tools that support .omwaddon files, though one can merge lists with the usual Windows tools if only .ESP/.ESM files are involved.

Playthroughs and Demos[edit]

OpenMW is stable and feature-complete enough that it has been used to make playthrough ("Let's Play") videos.

From the developers:

  • Release Commentaries — summary description and demonstration of significant changes in new releases; for both OpenMW and OpenMW-CS
  • Feature-Specific Videos — often showcasing recently-implemented features which have yet to be released

Future development[edit]

Built-in support for leveled list merging is a Wish-List item for post-1.0 release, though volunteer developers are free to work toward implementing it sooner.

More goals for the project include adding new scripting capabilities that exceed those of MWSE, but this is also slated for after the v1.0 release.

It will also be ported to more Unix-like platforms, including *BSD, iOS, and Raspberry Pi; this is largely dependent on individuals attempting to compile it and providing feedback about issues that arise in the process.

OpenMW-CS remains rudimentary as of early 2017, and is primarily a debugging and tweaking tool at this stage, and very much experimental alpha-stage software.

There are plans to enable the engine to also be used to develop entirely new, distinct games, after the v1.0 release

OpenMW is also the client-GUI used for TES3MP (discussion, source-code), a multi-player–capable fork, which already has basic functionality in public alpha tests since August 2016.

If you encounter problems, then consider submitting bug-reports to help; the developers are keen to fix things, in order for OpenMW to become a comprehensive replacement. Feature ideas go on the Wish-List.