Out of nowhere and with no announcements, Gaijin Entertainment, the makers of the popular MMO War Thunder have just released the source code to the underlying game engine Dagor Engine. The project is hosted on GitHub under the BSD-3 open source license. This move is unusual as Dagor Engine is still very much in use today, in fact War Thunder is one of the top 10 most popular games on Steam currently.
Details of the Dagor Engine from Wikipedia:
The Dagor Engine is a proprietary game engine used by Gaijin Entertainment in War Thunder, Enlisted, CRSED: F.O.A.D. and other titles. It was open sourced under permissive FOSS license in 2023. The original version of the engine was developed by Gaijin Entertainment and in 2005 the separate company Dagor Technologies was established for continued development. Currently the engine incorporates technology such as the PhysX physics engine and has been updated to version 6.5 since the release of War Thunder.] Gaijin’s Hungarian office is responsible for the further development of the engine.
The Dagor Engine does not come with any documentation beyond basic building instructions, although sample projects and precompiled tools and samples binaries are now provided.
You can learn more about the open sourcing of the Dagor Engine, that powers War Thunder and other games from Gaijin Entertainment, and get a brief introduction to navigating the source code in the video below.