Robot Alchemic Drive aka R.A.D. on the PS2 made by the good people who brought you EDF. This game definitely has issues but its got so much charm and in my opinion the most ambitious anime mech game ever made.
Video from someone running it on an emulator.
You control a human guy and have a remote control for the giant mech. But the catch is you need to position yourself to then stop and have a good view of your mech, the enemy mech and the landscape to fight. IIRC the controls for the mech were essentially rock em sock em robots style where the analog sticks control the arms of the mech and the R and L trigger buttons were your legs. Its basically playing a Pacific Rim-type of game and all of the buildings are destructible (something that would later be reused in the EDF games to great effect). You have to be careful because the enemy could take out the building you're standing on so then you would have to move to get a better vantage point.
Nothing really has ever rivaled this game to me other than I guess Chromehounds, but its an entirely different experience.