[ShinMegami]

Only ones I can think of off the top of my head are eden eternal and atlantica for mmos.

Eden has a neat concept, you can switch classes at any time and the game encourages it, and can be fun for a bit, though if it's anything like I remember it has a fairly big bot problem. The crafting gets a bit expensive later on with a fairly high chance of failure too, didn't feel much progress with later gear sets either.

I'm kind of reluctantly suggesting atlantica, once again, it's a neat concept where you can control up to 9 characters at a time and the game is fun up until around 90ish or so. Much past 100, have fun getting destroyed by at level content unless you spend a crap ton on their very expensive cash shop lolboxes with 20+ items in them (boxes are roughly 10 to 17 bucks a pop, the really good mercs? about 70 bucks 8D).

that said, can't think of anything massively great to play mmo wise that'd be free to play.