GURPS - Mecha

From their website:

"The Mecha Are Here!


From battlesuited space marines making an orbital drop to cinematic Japanese anime action featuring giant walking tanks piloted by beautiful alien princesses, GURPS Mecha covers the entire genre of mecha action! In the pages of Mecha you'll find:

• An easy-to-follow step-by-step guide to building mecha.
• Advanced rules with a plethora of options like transforming and combining machines that can turn into cycles or fighter planes, overload boosters, psionic mecha, energy battlesuits, giant swords and shields, even steampunk mecha!
• Character creation rules for mecha-genre characters and cinematic aliens.
• Advice on using mecha in everything from alien invasions to superhero campaigns, and suggestions for running anime-themed adventures.
• Special combat rules that emphasize the cinematic nature of mecha combat, as well as realistic rules for sensors, weapons and orbital drops.
• Sample mecha and battlesuits.
• And a detailed campaign world, Cybermech Damocles!"