Babel Sword is a shoot 'em up/versus fighting game hybrid created by Shiyo Kakuge using the M.U.G.E.N fighting game engine for the PC. It was only released in Japan. The player controls a selectable M.A.R.S., mechs not unlike gundams, to take one of five sides in a conflict over Earth's resources. The game is notable for being the only hybrid of the two genres made for the engine, an irony given the engine for fighting games was originally designed for shooting games. The game requires the engine be downloaded separately and to have the EXE and dlls put in the root folder to function (this is due to the engine's EULA).

Gameplay is not unlike that of WarTech: Senko no Ronde. The player selects a pilot and a M.A.R.S. (Machines of Assured Resourceful Structures, the game's gundam-like mechs). While pilot selection has no effect on the gameplay at all, each mech fights in a very different manner, making for variety.