Portal seemingly doesn’t even have a story.

After all, it’s a fairly short game, it doesn't give much direction, and it certainly doesn't provide overt backstory. You really have no context for what is happening -- the game makes its own rules.

But Portal contains much more than simple puzzles and a funny-sounding artificial intelligence with a mean streak. It not only raises questions about great game design, story, and character, but it conjures up philosophy about who we are and what our roles are in life with respect to one another.

With the long-awaited sequel now weeks away, it’s a good time to reflect. How does Portal explore narrative, and what can other developers learn from Valve about how to tell a story? Here are a few ways....

No exposition

Exposition is one of the worst chores a writer must trudge through when telling a story. It’s extremely difficult to do well, mostly because it’s so obvious and tacky -- it’s hard to hide, and even good writers suffer while trying. But Valve manages to side-step that by letting Portal’s level design and GLaDOS do the work for them.

When you first wake up, you find yourself in a test chamber. You get no instructions. You get no on-screen clues telling you which keys to use. All you can do is move around and play with the few objects in the room.

The only hint you see of any higher power is the name “Aperture Science” on a mug.

As you go forward through the level, you see empty chairs and desks, abandoned papers, and empty watch posts -- whoever was here evacuated in a hurry.

The game doesn't flood players with information when they first start, and it provides them an opportunity to discover more about the world around them, which is what gaming should be about.

The most important aspects of the game, such as the name “Aperture Industries” and the actual gameplay mechanics, are explained in enough detail for the player to be comfortable. But everything else is only hinted at. The lack of exposition makes the player keep moving.

Subtext revealed through subtlety

Good stories require subtext – they need to be more than just an excuse to shoot people or create mayhem. Portal doesn't just use subtext to reveal the actual reason why the player is completing the test chambers -- the game does so in a subtle way that rewards exploration.

You first realize there’s more to GLaDOS than expected because of some strange comments she makes:

The next test is currently unavailable. It has been replaced with a live-fire course designed for military androids. The Enrichment Center apologizes and wishes you the best of luck.

GLaDOS’s use of black humor puts you slightly on edge; you begin to feel your guide isn’t actually the comforting presence you thought it was.

In the later test stages the player sees broken panels, which allow passage into the areas behind each test chamber. Here you see writing scrawled on the walls: “the cake is a lie.”

Yes, this has become a silly Internet meme. But this line provides the most impact when it’s read in one of these secret chambers -- it’s the first time you realize you’re not a voluntary test subject. You’re completely trapped, alone, and in danger.

The art design in these chambers provides some subtle tension: cans of beans strewn across the floor, crumbled pieces of paper, and markers counting the days. As the player slowly discovers these areas and listens to GLaDOS’s taunts, the truth becomes clear.

Because none of this is actually told to you outright, the sense of mystery and subsequent dread is that much higher. This is the same technique used in horror games: what you don’t see is scarier than what you do, and in Portal the lack of information you have about your surroundings provides the threat.