This seems like something more for the help or discussion area of the Roleplay Institute. You can use this link
, which can also be found as the listing named Request Thread Moderation at the bottom of the page under the Site Functions heading, to ask for this to be moved.
That's a pretty huge question, but very easily answered. Roleplay genres are pretty much the same as literature genres, including specialized ones like 'cosmic horror' and 'steampunk fantasy' and so on, with the notable addition of fandom works that few would classify as a legitimate genre of literature. Literally all you need to do is go figure out what elements are core to the identity of a couple genres, then slap those two things together.
The heroic fantasy/sword and sorcery subgenre of fantasy is all about larger than life sword-wielding heroes where the tales focus mainly on personal battles rather than world-ending conflicts, and there's usually some magic and supernatural elements and romance in there. The mecha subgenre of science fiction is all about people getting into big robots and fighting each other and/or monsters. Combine them together by making all the fighting done in mecha that use huge swords and fight against huge monsters, but make sure it focuses on the personal story of the heroes rather than on some apocalyptic conflict and be sure the foes are supernatural and/or magical foes, plus include romance opportunities. Boom, sword and sorcery mecha genre meld complete.
As for a full list and detailed description of all genres, eh, that's a hell of a lot of work. Go search the internet for lists of literature genres and subgenres and you should be able to find some useful ones.