well, i haven't found it but i got some idea for your game.
First, give us the choice to choose the faction we want to play.Add good/bad stat to both side (like one team have special ability to regenerate if they are near another special unit...)then the game start when the fist battle is going to end( and will be used as a tutorial and wil show the player what his robot could look like upgraded to the max) so the player will feel more enthusiast to come back later stronger.
after that, you launch the intro that will show you the planet 100 years later.You could start with a small robot trying to kill other robot to get some scrap part to upgrade it till you can go back in space.With each upgrade you can choose whether your robot will be for offensive or for defensive with some special perk.
Game would be more fun if it is open world and you can encounter Smaller/Bigger robots that you will fight later when you will be strong enough.
Kind of Spore with robots.