In the first half of the game, you're an unnamed member of a ragtag group of humans, driving one of four vehicles in each mission: jeep (all-purpose assault vehicle), tank (slow and powerful), fire truck (filled with wa-wa), or buggy (light and agile). In the second half of the game, you're a big-ass dragon, flame broiling everything you see with fireballs and napalm breath, and picking up vehicles to use as gas-filled bombs.
After a narrated montage of film footage to setup the premise, you're thrown into a tutorial to teach you the vehicular controls, which is when everything starts going terribly, terribly wrong. Reign of Fire offers an "advanced" scheme, in which the left analog stick controls the vehicle, and the right analog stick aims the weaponry, and a "simple" setup, in which the left stick handles both functions, and the square and X buttons accelerate and brake.
Advanced should have been car-relative, so that pressing up on the stick always made the vehicle go straight ahead, and pressing left and right always steered in those directions; instead, it's a baffling, lethargic, FPS-ish system in which the vehicle (usually) moves in whatever direction you're pressing the stick. It's entirely counterintuitive and incredibly frustrating, and you're never in direct control of the damn car. The simple controls are equally sluggish, and all but worthless, since you can't aim in one direction and shoot in another, an essential strategy for survival in the later levels. Note to Kuju Entertainment's design department: you might want check out Twisted Metal, which had a perfect car-combat control scheme seven freakin' years ago.
The first few of the game's 16 levels are utter chaos, as military leader Van Zan (McConaughey's character in the film, voiced here by an adequate substitute) screams orders at you through your in-car radio. These are the most enjoyable levels of the game, as you frantically fend off a seemingly infinite number of dragons with your mini-gun and weapon pick-ups including raptor-like beasts that run along the ground and head-butt your vehicle, pterodactyl-ish creatures that fling exploding fireballs at you, and massive fire-breathing monsters that saturate the earth with their "natural napalm." Blasting a dragon out of the sky with a rocket (ludicrously hard) or a heat-seeking missile results in the game's most satisfying moment, as the slain beast slams into the earth like a crippled B-17.
Later missions are less hectic and more structured, at which point you'll notice that some of the mission goals are completely unaffected by your actions. For example, an early mission sends you out in the fire truck to retrieve a group of farmers. Several of the unfortunate seed-sowers have been set ablaze by the attacking dragons, and they continue to run in circles and do their "human torch" impressions for as long as you decide to let them burn.