This is a game I've dabbled with off an on over the years, and have even gotten to play in arcades a few times. What stands out for this is definitely the controls. You maneuver a robot in an open-space one-on-one 3D fighting arena, but the controls utilize two joysticks (or "twin sticks") for a sort of tank-like movement (but faster than you might expect). You push both joysticks in the same direction to move that direction, and you push them in opposite directions to turn (e.g. left stick forward and right stick backward to turn right). You kind of imagine the joysticks as your shoulders, and it makes more sense. You also jump by pushing the joysticks away from each other (left one left, right one right). And then you have the triggers for your weapons, which will vary depending on which robot you select.

It's a tough game to get the hang of, but even when I do terribly it's still pretty fun. I played a lot of it in Yakuza Kiwami 2 (via the Club Sega arcades), and though I could never win the whole arcade mode I did get a better feel for how each robot plays. All in all it's a solid early entry for the world of 3D arena fighters, and is one of those sorts of games that I don't feel has ever been emulated elsewhere that closely. I get the impression this series made a much bigger splash in Japan than anywhere else (being the home of Gundam, Macross, and the like), with the unusual controls perhaps keeping it from becoming a worldwide hit. I say give it a shot if you can, and try to stick with the "twin stick controls" option if you're playing with a home console controller.