the link only give basic intro from every anime non srw*
Super Robot War begin in Gameboy, the story about a bad guy (mecha) fighting a good guy (mecha). In this first SRW, you only control the mecha/robot. Which there is no human inside. In the end you fight the last boss who created this disaster.
Next in Super Robot 2, You no control the mech itself but use a pilot to control the mecha. And again, evil has attack the world. The story is more intense, but the changes are less.