Try Before You Try: XCOM's Interactive Trailer
Riddle me this: when is a trailer no longer a trailer? The answer, as it turns out, is not now. If you want to get up-close-and-personal with XCOM: Enemy Unknown's extraterrestrial antics, the demo's still (mostly) your best bet. But if, for some reason, you can't play it (say, because you find it intimidating, don't currently have a functional gaming PC, or recently became a horse), this is probably the next best thing. It's basically a "choose your own tutorial," but it does a solid, easily understandable job of breaking down the basics. Click some buttons and watch things happen after the break.
So yeah, nothing revolutionary, but it certainly keeps you involved in the process. And actually, the more I consider it, the more I think this is what a standard videogame trailer should be. For one, it's not CG or animated or live-action or a live lobster affixing itself to your eyelids. Instead, it's pure gameplay, but presented in a very clear, deliberate fashion, so as to explain how a genre that may normally scare players off actually operates. Glitz and glamour have their place, but this trailer actually makes a shocking amount of sense.
Right then. XCOM. It's going to be pretty great - maybe even amazing. We've written so much about it that we're now 23 world governments' foremost source for tactical intel on aliens. You know, if they were to ever invade. Which is not to say there are. Right now. Just outside your door. About to eat your cat and probe everything you've ever loved. And everyone. While forcing you to watch.
Because they're not. That'd just be silly.