Any rpg game thar has transformation as the central gimmick?

I know of quite a few games where this sort of thing is an option, but not many where it's the core gimmick of the system.

Last Stand is a kind of Kamen Rider-ish game about people in customisable suits of bug-armour.

Princess: The Hopeful is a fan-made New World of Darkness game about transforming into Magical Girls to punch the forces of darkness. You can also make transforming dudes and dudettes very easily in Mutants and Masterminds.

You could always play Champions and buy the powers with appropriate Limitations.

when you transform will your enemies see you naked?

>>51338159
of course