Alien Spawn

When reviewing a game, it can be really tempting to describe it as Other Game 1 plus Other Game 2. "Fallout 3" is just "Oblivion" plus "S.T.A.L.K.E.R.," "Mass Effect 2" is basically "Gears of War" with dialog trees, "StarCraft" is "Command and Conquer" plus South Koreans. You get the picture.

But even though it's easy and fun to do reviews this way, most people try to avoid it, as it's generally considered unprofessional. Generally.

But every once in a while a game just begs for this kind of comparison. "Alien Swarm," Valve's Source-engine update of a popular Unreal Tournament 2004 mod, is one of those games: It's "Left 4 Dead," played from a top-down view, set roughly 30 minutes into the movie "Aliens."

You all saw "Aliens," right? A distant human colony drops out of contact, so a tough-talking, diverse group of space Marines is dispatched to investigate the problem -- only to discover that all the colonists are being used as living incubators by a swarm of aliens that is much more dangerous than previously thought.

"Cut the power? How could they cut the power, they're animals!"

That's exactly what's going on in "Alien Swarm," needless to say. The game makes repeated attempts to establish an overarching plot between the missions, but that tends to get ignored in favor of the four-man killing spree made popular by, you guessed it, "Left 4 Dead." Some assets from other Valve games are recycled as well. Aliens explode exactly like the antlions in "Left 4 Dead 2," and "Half-Life" veterans will instantly recognize the sound of crates being broken (duh, of course there are crates in this game). A few of the "Half-Life" series' other notorious design elements also show up in this game, including:

1. Waiting for an obnoxiously slow elevator while being swarmed by aliens.

2. Waiting on an obnoxiously slow elevator while being swarmed by aliens.

and

3. Cheesy physics puzzles.

Fortunately the infamous "Half-Life" seesaw doesn't make an appearance; the physics puzzles here are more along the lines of "shoot explosive barrel A to knock loose heavy object B, which will fall/swing/roll into obstacle C, clearing your path." Also, following in the proud tradition of nearly every shooter since "Doom," there is one point at which your team will have to spend the entire level mucking about in the sewers. Just because.

"I hate sewers."

I'm sure it sounds like I'm being pretty harsh, but it's just good-natured ribbing. "Alien Swarm" knows it's derivative, and doesn't try to hide its influences at all. And why should it? "Aliens" is a great setting for a xenocidal romp, "Left 4 Dead" perfected the concept of four players teaming up against impossible odds, and the two work well in tandem.

Of course, when a "Left 4 Dead" game tells you to team up, you damn well better take its advice. Players who wander off alone -- even if they're really talented -- will get picked off by zombies faster than the unattractive characters in a slasher flick.

But while "Alien Swarm" is still a very team-oriented game, it's not as punishing for the Rambo types: A skilled player can survive just fine on his own for extended periods of time, only coming back to the group occasionally to get healed by a medic. But there are "L4D"-style climax events scattered throughout the levels that can be extremely difficult for only one or two players, so teams that like to spread out will still be forced back together at regular intervals.

At first I thought this lack of cohesion was a weakness, but it actually turns out to be beneficial when some of your team start getting killed off; many of my games on harder difficulty levels have ended with one or two bold survivors dashing frantically for the exit amid hordes of enemies while their dead comrades cheer them on. Good fun.

What's even better is that, if you actually plan on getting into these sorts of situations, the game's got you covered with its customizable loadouts. Each player has three item slots (two weapons and a special item) to carry anything they might need for the mission. This doesn't start out very imaginative -- the default is a big gun, a smaller gun, and a health pack -- so I was a little worried that the whole inventory screen might consist of a couple dozen guns with slightly different damage or accuracy.

I was wrong. You can carry around toys like a stationary automated turret instead of a secondary weapon, setting it up to cover one entrance while you and your teammates seal off the others, or you can bring a welding torch in your special items slot to seal doors shut, buying precious time for your team until the swarm inevitably breaks through. There are also support items like group healing beacons or extra ammo satchels that will allow your entire group to be a lot less conservative in their play.

But all this is just the starting equipment. You also gain xp for every mission, which allows you to unlock the really interesting toys like the flamethrower or Tesla cannon that can quickly lay waste to large groups. You can set mines, unleash missile barrages, or even pick up a personal short-range teleportation device. And, yeah, there's totally a chainsaw. None of these items are measurably better than your starting equipment, but they open up a nice variety of tactical choices for different styles of play.

"We got tactical smart missiles, phase plasma pulse rifles, RPGs. We got sonic, electronic ball breakers!"

I remember one particularly tense mission that had been kicking my team's collective butt for quite a while. We finally got to the climax event near the end of the level, where the team's technician has to hack a computer system while his teammates defend him from waves of enemies. I was that technician; my teammates were all dead. So I quickly set up a turret to cover one door, welded shut a second one, and rigged up the entire room with proximity mines to blow up anyone who made it through. All of that lasted just long enough for me to finish the hack and pick up my fallen ally's flamethrower. Two seconds later the room was filled with enraged alien monsters; another two seconds and it was filled with deep-fried alien corpses, and a moment later I had sprinted out the door and finished the level. Yippee-ki-yay, you alien bastards.

That's the good news, now here' the bad: "Alien Swarm" is bugged. Since the first mission I played, my game has been having problems with the framerate. Sometimes it's just a less-than-smooth 15-20 fps, while other times it drops below 1 fps and my game is transformed into "Alien Swarm: PowerPoint Edition." It always comes in spikes lasting for about a minute each, in between which the game cruises along at a consistent 60 fps as though nothing were ever wrong. Given that my computer has been able to run all other Source games flawlessly at maximum settings, this is a bit confusing.

I've been researching this problem all week, and can confirm that it's a problem with the game, not with anybody's individual computer or internet connection, although some people do suffer worse than others (I seem to have it exceptionally bad). Tampering with the game settings doesn't make any visible difference, and the spikes appear to be pretty much random, but it's rare that I can get through an entire mission without encountering one. I'm sure I don't have to tell you what happens to a space marine who starts lagging in the middle of a battle.

"Game over, man! Game over!"

It's a testament to how fun "Alien Swarm" can be without this lag that I'm still playing it, even long after I got enough information to write this review. If you like four-player co-op but are sick of zombies, or if you ever wanted to see James Cameron's "Aliens" translated into videogame form, you won't find much better than "Alien Swarm."

I'm giving this a "try it" rating only because of the framerate problem; if you download this game and it runs smoothly, you're in for a treat. And if not . . . hey, it was free.

Available at Amazon.com:

The Saboteur

Alien Spawn

Video Games: Alien Spawn