After Fantasy, my favorite fictional Genre is Giant Robots/Mecha- I picked up this RPG ages ago, and I have yet to ever play it. In spite of this, its probably one of the best Mecha rpgs I've ever seen.
I've played in a short Mekton campaign (not the later Mekton Zeta) years ago when Mekton first came out. The game system was a bit klunky, although Zeta supposedly fixed a lot of the problems. As I never was much of a giant robot fan, I was mainly playing because someone else in my gaming group was running it, giving me a rare chance to play instead of GM. <g>
Maybe we could do an PBP game someday, if there was a enough interest.
If you can find interested people, feel free to start one here.