They take over the role of controlling a team and can therefore be seen as a machine equivalent to a human player but are of course less cunning. The engine supports Skirmish AI plug-ins to be written in a variety of programming languages. Currently these are Lua, C, C++, Python and the JVM languages like Java and Groovy. It is also possible to develop plug-ins to support more languages. Springs rendering features include deformable terrain, 3D projectiles and multiple water renderers. The unit files of Total Annihilation are compatible, allowing third-party units to be imported. The scripting language allows for a customizable gameplay and user interface modifications. Team Players can also draw and write on the game map to coordinate tactical moves with other players. The third-party AI allows for varying degrees of difficulty. Alternatively, the SpringRTS Lobby can be downloaded at mirrors. Source code Springs source code, licensed under the GNU GPL-2.0-or-later, is primarily written in the programming language C++, as is springlobby. An alternative lobby, TASClient, is written in Delphi, and there are lobby servers - used to organize multi-player games - written in Java and Python. The C++ code structure is written in an object-oriented manner and is documented to some extent using Doxygen. The official source code package includes project files for various integrated development environments (IDEs) and building tools, including CMake, KDevelop, Visual C++ 7.0/8.0, and Xcode. Reception and adoption Various games leveraging the Spring engine range from free content games with minimal restrictions on use and distribution to games with commercially licensed art, such as P.U.R.E. Additionally, content from Total Annihilation has been modified to run on the Spring Engine, although playing games that incorporate such content requires that one own a copy of the original Total Annihilation game. Spring has many games in various stages of development. Some are based upon and use content from the original Total Annihilation game, this includes the games: Balanced Annihilation, Tech Annihilation, NOTA, and XTA. However, there are many games which are derivatives of other works of fiction, such as a Gundam game, a Warhammer 40,000 game, and a Star Wars game based on the Galactic Civil War. There are also several fully original games, including "Expand & Exterminate", a strategic game inspired by Earth 2150, "The Cursed", a unique mixture of science fiction and fantasy, and "Kernel Panic", a Darwinia-esque game emphasizing simplicity. The website also