OTA

OTA, or the original Total Annihilation, is a game made by Cavedog in 1997. Spring was originally a remake of OTA in 3D, but has expanded beyond that. OTA still has a large community, and has many, many mods to play with. A few of these have been ported to Spring, such as Absolute Annihilation, UberHack, Final Fronteir, World Domination, and SWTA.

For more information, go look at Wikipedia:Total Annihilation.