A few months ago, I saw two new sci-fi movies at the San Francisco International Film Festival, and now both are in limited release: Duncan Jones's Moon (21 screens) and Aristomenis Tsirbas' Battle for Terra (2 screens). And it got me thinking. These two movies couldn't be more different, and the main distinction between them is this. Moon is sci-fi based on an actual sci-fi idea. That means that science actually figures into the fiction somewhere. And Battle for Terra is the perfect example of a war film decorated with sci-fi trimmings; its big "twist" is that the humans are the bad guys and the aliens are the good guys, but aside from that the story unfolds exactly like a regular war film. The aliens, spaceships and other gizmos don't really figure into the major themes or plot.

It got me thinking about how many science fiction movies are really just war movies in disguise. (The current Terminator Salvation is another one.) It's very easy to transform the combatants of a war to alien races and make the cause of the war something fictitious, like the "spice" in Dune (1984). It's much easier to explain why people are fighting over that powerful stuff than why they're fighting over differences in religions or beliefs. And it's much nicer to justify battling alien invaders than it is to justify humans fighting humans. Frankly, I'm all for this little bit of deception, provided the sci-fi movies have three things. Battle for Terra has none of them.

The first thing I like in a war movie is that it not be dreary and depressing. I already know that I'm opposed to war, so I don't need a movie to drip with importance and regret over the futility of it all. My favorite kinds of war movies aren't really even about war, but rather about the characters that are there. I like it best when practically nothing happens, like in Samuel Fuller's The Steel Helmet (1951); you can learn so much more about a war in its quiet moments than during its explosions. Kathryn Bigelow's current The Hurt Locker (4 screens) is one of the best war movies I've ever seen because of this factor. It's about day-to-day occurrences and the people who experience them, rather than sweeping generalizations.

The second thing I like is that the characters have some kind of personality that comes somewhere from real life, and not other war movies. There's an odd kind of military behavior that gets recycled from old war movies, and then re-incorporated into military life, and then used in movies again, until it's all a jumble of clichés. I don't need that stuff to sound accurate; I want it to sound authentic.

And my third thing is that, if you're going to disguise your war movie as a science fiction movie, do it in such a way that the science fiction actually gets used for something. Star Wars is probably the exception, since George Lucas more or less invented the idea of transferring war stories to outer space, and some of his science fiction ideas were pretty darn cool, even if they were treated as backgrounds passing through. No, I'm thinking of the original The Matrix (1999), which is essentially a war movie (it's about a rebellion) but with a crucial, centerpiece science fiction idea. That movie was clever enough that its idea could be intellectually and philosophically applied to real life, but enjoyment of the movie did not require any deep thinking.

If you can't put these things in your sci-fi war movie, then I'll pass. I'll just take a smart sci-fi movie like Moon instead.