Well, riviera is playable, but not fully. I can try say you can finish this game accidentally and it means really, accidentally. Trick is, movement works in someway, but battle system is too complicated, and menu changes everytime because of the teams you have selected and managed.
Imagine first battle have menu like: attack, magic, items, run away, next time it's: run away, attack, items, magic.
It is problematic because you want to attack, and you are trying to run etc.
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BattleTAG: Lirin#21759