"Doom: Resurrection," "F.A.S.T." show off the iPhone's gaming potential

Watch out, Nintendo DS and Sony PSP—the iPhone-as-gaming-platform is nipping at your heels. Exhibits A and B: "F.A.S.T.," a gorgeous supersonic airborne sim, and "Doom" Resurrection," a clever rethink of the classic first-person shooter.

First up: "Doom" Resurrection" ($9.99) from the FPS masters at id Software. Built from the ground-up for the iPhone (and originally conceived by id's John Carmack as an experiment—one that reportedly almost didn't see the light of day, in fact), "Resurrection" takes the classic Doom shooter formula and tweaks it for the touch-only iPhone, turning the game into an "on-rails" first-person experience that's surprisingly satisfying.

"On rails," you ask? What's up with that? Well, this may sound strange at first (and believe me, my initial gameplay experience was odd as well), but "Resurrection" plays a bit like an amusement ride. Instead of navigating movement and "look" controls (which is tough to pull off with the single analog nub on the PSP, let along the all-touch iPhone), your character's movements are predetermined—you'll see yourself walk forward, whirl around, open doors, and gaze around rooms, all automatically (and whether you like it or not).

At first, the "on rails" approach feels seriously limiting (what if you want to sneak down that corridor, or poke around those boxes in the corner?), but after blasting a few bloodthirsty creatures with the accelerometer-controlled crosshairs (other touch controls let you fire, change weapons, reload, dodge fireballs, and duck into cover), I found myself having a blast.

Of course, I'd prefer the freedom of being able to move around on my own, but Doom's "on rails" system leaves plenty of room for skillfully squeezing off shotgun rounds, ducking behind bulkheads, or shoving away grappling enemies by giving your iPhone a shake—and frankly, it works much better than the clumsy virtual joystick on, say, "Resident Evil: Regeneration," which leaves you with so many fingers on the screen that you can barely see what's going on.

Besides its clever control scheme, "Doom: Resurrection" boasts some of the best 3D graphics I've seen yet on an iPhone game—maybe not quite PSP quality, but pretty close, especially on the speedy iPhone 3GS—along with an atmospheric soundtrack and plenty of squisky sound effects. Great stuff.

Next: "F.A.S.T.," an aerial jet-fighter game (and a steal at $3.99) that bears a strong resemblance to "Tom Clancy's H.A.W.X." on the Xbox 360 and the PS3.

As with "H.A.W.X.," "F.A.S.T." (gotta love those acronyms) plunges you into airborne dogfights against both A.I. and human enemies (thanks to a four-person multiplayer mode over 3G, Wi-Fi, or local Bluetooth).

I've only played "F.A.S.T." on an iPhone 3GS, so I can't vouch for its performance on the 3G or original models. However, the graphics on the 3GS are startlingly impressive, with smooth rendering and hair-trigger responsiveness even when you're going head-to-head at Mach 2.

As with other iPhone games, you'll still have to rely on a fair number of touch controls—for firing missiles, releasing flares, adjusting your yaw, and so on. But what makes "F.A.S.T." so playable on the iPhone are the accelerometer controls, perfect for pulling out of a steep dive or performing hairpin turns to avoid incoming missiles. Indeed, I'm not sure how you'd go about replicating "F.A.S.T."'s gameplay with the PSP's controls, especially given its lone analog nub.

Now … does the iPhone have any games yet that measure up to, say, the epic grandeur of "God of War: Chains of Olympus" on the PSP? Not yet, if you ask me (although I've heard good things about the iPhone version of "Assassins Creed"). But both "Doom: Resurrection" and "F.A.S.T." (I keep wanting to call it "H.A.W.X.") ably demonstrate the iPhone's potential as a gaming platform—and from what I've heard about the iPhone 3GS's increased processing power, we ain't seen nothin' yet.

Note: While games like "Doom: Resurrection" and "F.A.S.T." look superb on the iPhone 3GS, they're like vampires when it comes to battery life—in other words, they suck it dry. Make sure you're near a power outlet or keep some battery boosters handy if plan on any extended "Doom" or "F.A.S.T." action.