Play Final Fantasy Sonic X6 Online
Dodging lasers as Shadow while Sonic charges a limit break—this Flash game somehow turns a ridiculous crossover into legit anime spectacle between the janky moments.

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Game Overview
Final Fantasy Sonic X6 is one of those weird, ridiculously ambitious Flash games that somehow pulls off being more cinematic than half the RPGs I've played. The opening throws you right into this over-the-top anime-style battle with Sonic and Shadow doing Final Fantasy-style limit breaks, and I remember just sitting there thinking, "Wait, this is a Flash game?"
The moves look shockingly good for something running in a browser—like someone mashed up Advent Children with classic Sonic sprites. You've got combo systems, quick-time events, and these absurdly long cutscenes that make it feel like you're playing through someone's fever dream crossover fanfic. Half the fun is just seeing what ridiculous scene they'll throw at you next (I won't spoil the one with Knuckles and a chocobo).
It's janky in places, sure, but in that way where the ambition outweighs the flaws. You'll either bounce off it in five minutes or lose an entire afternoon to it. Still the best of the FF/Sonic mashups, hands down.