Spring (formerly known as TA Spring or Total Annihilation: Spring), is a full 3D open source RTS engine originally created by the Swedish Yankspankers, intended to bring the gameplay experience of Total Annihilation into three dimensions. The core game engine is released under the GPL License; however, the prepackaged mod that comes with the standard installation requires that one own a copy of TA to legally play it. There is, however, an official release which uses fully free content, and there are a number of mods, both in development and released, that are also completely free to use.

Spring is being developed by the Swedish Yankspankers and the Spring community. The initial goal was to have the game run the mods and 3rd party units from Total Annihilation. This goal is now mostly complete, and the project has moved on to including additional features. The game is mainly focused around multiplayer games over the Internet or a LAN connection. There are currently no single player campaigns or missions, although there is some basic support for this through Lua scripting. There are also many skirmish AIs under development, allowing for offline play or extra players in an online game. Two skirmish AIs ship in the game package.