Possibly the worst of all the Final Fight knockoffs and clones, Riot Zone is an utter travesty.
Tony and Hawk (haha, get it?) are two undercover cops who take matters in their own hands after Tony's girl is kidnapped by a bunch of thugs---a generic plot that strangely resembles a similar dilemma found in Final Fight. Of course, get past all that and you're left with a crummy, half-assed beat'em up that crawls to the bone with waves upon waves of thugs that seem to repeat one after another--many with different color variations, but endless clones all the same. The potential of the Turbo Grafx CD is utterly wasted on this title--the only thing that pushes its hardware is the CD-quality music, and not even that is any good. Character animations are laughable at best, especially Tony--the dude with the mohawk--who walks as if he's hopelessly trying to shake some fire ants out of his tacky, orange-flavored crew pants.
Gameplay is as you'd expect typically of a Final Fight clone, and Riot Zone doesn't push any boundaries. In fact, the whole thing seems comfortable with being a shameless knock-off of the source material it blatantly rips from. Both fighters don't have a whole lot of moves aside from punching, kicking, throwing (you can't even hit your enemies when you're grabbing them), and a life-draining spin attack. Repetitive, boring gameplay kills the game's momentum, and you'll find yourself turning your console off long before you finish the first level.
Overall, Riot Zone was a game nobody asked for but we got anyway. To my knowledge, there are far superior Turbo Grafx CD games available for consideration, so it's somewhat perplexing as to why Nintendo would screw us out of higher-quality titles (i.e. the Valis series, Dracula X) and pander us with this crapulence. At any rate, if you're looking for a good beat'em up from the VC Catalog, there are much better, non-TGCD offerings that are worth your gaming money---like the far-superior Streets of Rage games.