Contra is a freeware modification for Command and Conquer Generals: Zero Hour real-time strategy game. It's a big project started in 2004. It adds many new units as well as numerous new upgrades, new general's powers and buildings. It also adds new sounds, maps, bug fixes, enhanced graphics, and other effects, as well as three new generals. There are lots of people playing in multiplayer.
The best mod for C&C Generals Zero Hour.It was the "mod of my dreams". E.g. I imagined a sniper who never reveals himself (unless spotted by radar) (Assasin), a SCUD(Elbrus) Launcher with unlimited range (Prince Kassad's Elbrus Launcher), a dual Nuke Launcher (Bertha, although it will be replaced with the Yanwang) a gattling tank firing anti-tank shells (Shaitan or Guan Yu).Also, I like the idea of the ranking system and, even more, the Super-units.It surely deserves a 10 ;)