Now, both the PSP and the DS share the same three-game story. In part one -- Duke Nukem: Critical Mass -- the Earth Defense Force has been sending agents to the future, but the agents haven't been reporting back. To figure out what the heck is going on, the Force decides to send Duke in to figure out what the heck is going on. When Duke gets to the future, he finds a world in ruin and ruled by alien captors. After some investigating, Duke discovers everything went to hell when he left because he left; when he took off, the aliens moved in. In the second game of the trilogy -- Chain Reaction -- Duke heads to the present to try and fix things, but apparently that doesn't go well because the third game -- Proving Grounds -- sends him to World War II.

On the PSP, the game controls like your typical third-person shooter. The face buttons control your point of view while the nub moves Duke around his 3D world. R shoots, and down on the D-Pad lets Duke leap over obstacles and such. I got to take Mr. Nukem, clad in a red tank top and trademark shades, through two levels. The first was a screwed up city. The roadway was bent into the sky, craters were in the street, fires were burning, and so on. Every now and again, a pig-faced alien in bib jeans popped up and I shot it in the head. When one of the beasts got a shot off on me, a splotch of blood popped up on the screen. After that short experience, the demo jumped to a level where Duke was wearing a jetpack and shooting through the sky. In this version of the game, the jetpack is on rails and always moving forward, but in the retail release, it'll be a more open-world environment. For now, Duke could push forward and fire machine guns and rockets at the flying pigs. You'll be able to play this PSP adventure as a strict third-person adventure, anchor the view to an over the shoulder perspective, or duke it out from the first-person perspective.

On the DS, Critical Mass is a 2D-ish side-scroller. See, that description's a bit too general for my tastes. Apparently, Critical Mass is going to employ several different types of controls and views. The basic perspective is the 2D one I tackled this evening. Duke started at the left side of the screen, moved to the right, and blew away the few pig-faced aliens that popped up. However, when I hit the L or R button, the camera panned in that direction so that I could see what was coming up or creeping up behind me. When I was about to cross an alleyway, Duke put his back to the wall and a set of crosshairs popped up in the alley. I could move the crosshairs, pull the trigger, and Duke would pop out to shoot. In another section of the game, Duke manned a mechanical sniper rifle. Via the touch screen, I zoomed in on the top-screen target and repositioned the crosshairs with a pair of stylus-controlled levers. Outside of this sniper stuff, the touch screen will be used for weapon selection and monitoring how much health and armor you have.