At heart, Portal is a puzzle game that adheres religiously to the traditions of the genre. You must navigate blocky 3-D obstacle courses while avoiding various hazards and tripping switches with weights — often in cunningly difficult sequences — while trying all the time to keep from falling off a ledge into the fatal muck below. This is quite standard puzzle gruel.

It’s the teleportation that transforms the game, because it allows the designers to craft challenges that seem, at first, flatly impossible — until you grasp some of the deeply odd tricks the portals let you accomplish.

For example, one stunt I used frequently involved setting up a portal somewhere high above me on a wall. Then I’d jump off a cliff, start falling — and then open a portal precisely at the spot where I was due to hit the ground. My momentum would blast me out the portal high above the ground, shooting me like a bullet through the air to a far-off ledge I couldn’t otherwise reach.

The game constantly challenges you to invent ever more paradoxical feats of self-propulsion. I used the same momentum-gathering technique to bounce myself vertically upward out of a hole in the ground, and then, while flying through the air, shoot another portal in a nearby piece of ground. (Think of a groundhog popping in and out of his hole, except the holes keep moving.)

The upshot is that Portal, perhaps inadvertently, makes for a hell of an educational game — because you’re constantly mentally calculating the vectors of force and direction you’ll generate by falling through and out of strategically placed holes. Physics teachers could have an absolute field day with this thing — using it to help kids grasp, in a really visceral way, how Newtonian laws of motion work.

Extreme physics-geek warning here: A decent teacher would have to point out that teleportation violates the law of conservation of energy. When you teleport yourself up high on a ledge, you’re effectively “creating” potential energy out of nothing — which is impossible in the real world. Yet this, really, is the genius of the game. The game designers produce their coolest tricks by ruthlessly adhering to most of Newtonian physics but then cleverly violate one key rule — thus allowing you, the gamer, to explore what happens in such a world.

This is precisely the sort of mental thought-experiment that really well-designed games can provide.

Indeed, as I played, I experienced a ton of other delightful “aha” moments, as I deduced clever new ways to use the portals. I’d coax an enemy to fire at me, then use a set of portals to reroute his bullets back at him. (Insanely satisfying.) In another situation, I was trying unsuccessfully to crane my neck to get a view of a remote upper level. Then I realized I could open a portal high on the wall, and use it to simply peer through. Presto: the portal as a surveillance device.

Personally, I hope Valve — or some other game designer — takes this concept up a notch. Why not use this game mechanic to shake up other well-worn genres? Imagine a first-person shooter where you can trigger portals on the fly, popping through them to snipe an enemy. Or think how weird a Mario racing game would be if you could shoot portals that wreak havoc on the racetrack? (And hey — since I find pro sports kind of dull, I suspect football, basketball and soccer videogames could all be awesomely torqued if you allowed players or coaches to generate a few portals.)

Extending the conceit to other forms of gameplay would also give the concept of portals new life. Because as much fun as Portal is, it’s not really something you’re going to want to play for more than five or six hours. It’s more an object lesson in breakthrough game design. Tweak one part of a well-worn game mechanic, and presto — you can open a door to something really new.