Bouncing Zabaglione Bros.
Legend
A new, Mech-based FPS has been announced, Hawken. Looks pretty advanced so far.
Unfortunately it looks like its multiplayer only
Yeah it looks like Shogo style Mech action. Mechwarrior was more tanks-on-the-battlefield style gaming with mechs out on open terrain or expansive cities and most of the mechs were beefy lumbering juggernauts (there were some little speedy jump-jetting mechs though). Mechwarrior also felt like a serious simulation of a complex vehicle and war scenario, unlike Shogo which felt like a shooter.
I never tried Heavy Gear.