Spring (formerly known as TA Spring or Total Annihilation: Spring), is a full 3D free/open source RTS game engine originally created by the Swedish Yankspankers, intended to bring the gameplay experience of Total Annihilation (TA) into three dimensions. The core game engine is licensed under the GNU GPL.
Games are played using one of a number of mods. The standard installation comes with a range of prepackaged mods, some which requires that one own a copy of TA to legally play them, and other Free Content mods which may be used free of charge without owning a copy of TA.
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, and serving as a more general RTS engine. Most of the games are mainly focused on multiplayer. There are currently a few single player missions, built on the basic support for this through Lua scripting. There are also many skirmish AIs, allowing for offline play or extra players in an online game.
Spring's source code, licenced under the GNU General Public License, is primarily written in the C++ programming language, as is springlobby. The default lobby for windows, TASclient, is written in Delphi, and its current game server which is written in Java. The C++ code structure is written in an object-oriented manner and is documented to some extent using doxygen. However most of the code has no proper documentation yet. The official source code package includes project files for various IDEs and building tools, including CMake, SCons, KDevelop, Microsoft Visual C++ 7.0/8.0, and XCode.
Spring is designed to be played as online multiplayer matches. It uses a deterministic game simulation which is executed on all game clients. Only the user commands are sent to other players, which prevents any active cheating. AMD-64 and i386 platforms are supported for multiplayer on Linux, and i386 on Windows.
The game uses a lobby with a look and feel similar to an IRC client.
The lobbies for the game allow setting up singleplayer games as well. This can be done either by using a special single player mode, or using the multiplayer mode with a password and adding bots to the game. Instead of using bots, some mods also support special game modes that let you play singleplayer. Most popular in this area are the chicken modes of CA and BA, where you have to defend against randomly appearing monsters. Since version 0.79, Spring also features missions.
Skirmish AIs (aka AIs, or Bots) are needed to get a normal singleplayer game running. They take over the role of controlling a team and can therefore be seen as a machine equivalent to a human player. The engine supports Skirmish AI plugins to be written in a variety of programming languages. Currently these are C, C++, Java, Groovy and Lua. It is even possible to write plugins to support more languages.
- Battles with up to 250 players, and 50,000 units.
- Large, highly detailed maps in full 3D with deformable terrain, forest fires, dynamic, bump and reflective water, and custom skyboxes.
- Several camera modes, allowing for anything to be viewed from almost any angle (including First-person unit control).
- Full 3D combat in land, sea, and air, with realistic weapon trajectories (physics engine).
- Many different Games/Mods made just for Spring.
- Complex 3rd party AIs of varying levels of difficulty.
- Fully customizable gameplay and user interface via Lua scripts.
- Ability to draw and write on the map for better tactical communication.
- Compatible with unit files from Total Annihilation, allowing 3rd party units to easily be imported.
Mods and games
Spring has numerous mods in various stages of development. Most are based upon and use content from the original TA, including the most widely played mods: Balanced Annihilation, Complete Annihilation, NOTA, and XTA. However, there are many mods which are derivatives of other works of fiction, such as a Gundam mod, a Warhammer 40,000 mod (with another in production), and a Star Wars mod based on the Galactic Civil War. There are also several fully original games, including "Expand & Exterminate", a strategic game inspired by Earth 2150 and Kernel Panic, a Darwinia-esque game emphasizing simplicity.
This is the most prevalent mod that is used by the online Spring community. It features all the previous units from "vanilla" TA, plus several extras for each faction.
As the name suggests, the mod rebalanced Absolute Annihilation, which was a rebalanced version of the TA mod Uberhack. The unit stats have been modified from Uberhack's base stats making it very dissimilar from TA's Uberhack. The balance does not reflect TA gameplay as much as an augmented version of TA.
Star Wars: Imperial Winter 
Featuring over a hundred different units for the Galactic Empire and Rebel Alliance, spanning from The Phantom Menace to Return of the Jedi, SW:IW aims to not only recreate the epic battles and rich universe of Star Wars, but also offers innovative and interesting design features such as asymmetrical sides, realistic weapon physics and a territory-based resource system designed to target competitive gamers as well as Star Wars fans.
The production is currently in a closed Beta as of January 2009.
Not to be confused with the ATV game Pure, P.U.R.E. is set in a time where humans were at war agaist an evil AI called the Overmind. It is developed by a single person, known by the Spring community as Argh. The game features up to 57 unique units, new and improved GUI, unique resource system and 2 different sides, and a main menu (though not in-game). P.U.R.E. is featured in ModDB and several other review sites.
P.U.R.E. at present (October 2008) is at the RC (Release candidate) stage.
Complete Annihilation 
Humanity left a final legacy before its extinction.
Two "species" of autonomous and reproductive robots fight perpetually for control of their bleak, nihilistic galaxy, doomed by their creators to stay locked in conflict until the entropic heat death of the universe.
Spring: 1944 is one of the furthest-developed games on the Spring engine, and as the name suggests is based on the later years of the Second World War. It contains nearly 300 unique units across the four major belligerent factions (USA, United Kingdom, Nazi Germany and the USSR), with all content being produced by several main developers and a handful of contributors, and is the most popular independent production project on the Spring engine. Unlike most conventional WW2-themed real-time strategy games, Spring: 1944 is heavily "epic" in scope, with players commanding hundreds of units and multiplayer team games involving thousands of infantry, vehicles, tanks and aircraft.
- Spring homepage
- Spring on GitHub
- spring-portal.com (download all necessary spring-files like installer, maps and mods)
- spring.jobjol.nl (download location for maps and mods, etc...)
- Spring on BerliOS (outdated)
- IRC Channel: #sy on irc.quakenet.org
- SpringLobby, a crossplatform lobby client for spring.
- setup guide for spring on linux