A lone marine stalks through the corridors of a ruined military facility, pulse rifle at the ready. His motion tracker screams, warning him, just in time, of the xenomorph charging at him from behind. As it closes, all teeth and fangs and screaming rage, he opens fire, hoping desperately to drop it before it reaches him. Sound like a familiar scene? Despite appearances, it's not a new Aliens vs. Predator game, it's Shadowgrounds Survivor, the follow up to last year’s Shadowgrounds, a top down shooter in the mold of Crusader: No Remorse.

If you've played the first game in the series, you'll have a broad idea of what to expect in the sequel: frantic shooting action as you attempt to repel hordes of enemies, mission-style objectives, and a storyline cribbed directly from Aliens. Not that the storyline matters too much, of course. This is one of those games you play for the action, not the plot; and here Frozenbyte bats it out of the park.

The story mode remains well balanced and exciting, and as your character advances, you'll gain both character and weapon upgrades. New this time is the inclusion of three different protagonists, each with their own unique weapons and abilities, though in practice, each character ends up with one third of the full arsenal from the first title. The roster is what you'd expect from a game of this style: a marine, focusing on rapid fire weapons and heavy artillery; a sniper, focusing on speed and long range lethality; and the man they call 'Napalm', who, well, let's just say he lives up to his name. Each of the protagonists features unique upgrades and special attacks, changing up the game play in unique ways. The sniper, for example, has a special attack called 'Killing Frenzy'. When activated, it puts you into a brief period of bullet-time, and causes your rail rifle to kill all non-boss enemies in a single hit.

Also new to the series is the 'Survivor' mode, a welcome nod to classic arcade shooters. Survivor mode, as the name implies, is all about staying alive as long as you can. In our preview copy, only two survivor levels were available, but each takes place on a unique map, tailored for the character whose life you attempt to preserve. The first map was a tactical affair for the Sniper, with long sight lines to take advantage of her rail-gun and sniper pistol. The second was a brutally claustrophobic affair starring Napalm, the tight quarters and limited space showing off his flamethrower and shotgun (He likes to keep it handy for close encounters) to brutal effect. The survival maps start easy, but quickly increase in difficulty, as the alien hordes begin appearing faster, and you begin to exhaust your ammo supplies. The survival maps aren't pure adrenaline fests, however. There's an element of strategy to clocking in the best survival times, which depends upon your ability to control the map, and use the existing resources to your advantage. Sniper has NPC backup with infinite ammo, while Napalm's map has a central area surrounded by glass walls: quite useful to funnel your enemies, assuming you can avoid breaking them.

The mission mode has also seen some improvements and alterations. The game still makes fantastic use of light and shadow, both for atmosphere and ambushes, and it's still one of the prettiest top-down shooters around. The game now includes support for the Ageia PhysX physics processing unit, as well as a software emulator for the vast majority of us without the PPU. The enhanced physics engine is used to good effect in the game, enabling scenery-throwing explosions, flying bodies, and the construction of makeshift obstacles (with a few lucky grenade tosses). It's part of Frozenbyte's effort to put their sequel in a more fully realized 3d-space. It's no longer enough just to watch your front, back, and sides, as aliens can now come at you from below; literally scaling the walls of cliffs to ambush you. In addition, an old friend from the first title makes a return appearance, with some new loyalties. This time, instead of having to fight the minigun-toting security bot, you control it in a satisfying change of pace. Instead of running from the alien hordes, you stalk them, scything them down like wheat at the harvest.

Assuming there are no delays, Shadowgrounds Survivor is scheduled for release in late 2007. We'll be waiting, pulse rifles in hand.