For better or for worse, the previously-released previews and promotional material for next February’s big screen treatment of the hit sci-fi novel I Am Number Four have thus far sold the movie as essentially being Twilight with aliens instead of supernatural creatures.

A third theatrical trailer has been released for producer Michael Bay/director D.J. Caruso’s alien teens with superpowers pic – one that’s all the more interesting because it focuses more on the main character’s other worldly heritage and attempts to control his deadly abilities.

Here’s the official synopsis for I Am Number Four:

Extraordinary teen John Smith (Alex Pettyfer) is a fugitive on the run from ruthless enemies sent to destroy him. Changing his identity, moving from town to town with his guardian Henri (Timothy Olyphant), John is always the new kid with no ties to his past. In the small Ohio town he now calls home, John encounters unexpected, life-changing events—his first love (Dianna Agron), powerful new abilities and a connection to the others who share his incredible destiny.

The second theatrical preview and behind-the-scenes featurette for I Am Number Four focused more on the budding romance between the inhuman Smith and human gal Agron. Their relationship does look different than that of Bella/Edward, but not so much that the Twilight comparisons are that much of a stretch, truth be told.

Now we have a trailer that offers more information about Smith’s experiences before he arrived in Ohio and how, like the young mutants in X-Men: First Class, the young alien must deal with the pangs of being a socially-isolated youth – and that there are beings that want him dead simply because of the abilities he possesses.

Watch the I Am Number Four trailer (via Apple) below:

Most of the action and F/X-heavy footage released from I Am Number Four so far looks decent, if not extraordinary. Pettyfer doesn’t appear to be the most expressive of actors, though his role in the sci-fi thriller might not require him to do much more than act like a frustrated, moody high schooler – and provide some eye candy for those uninterested in explosions or aliens that can shoot laser beams from their hands.

The mythology of the aliens in I Am Number Four is intriguing, especially the bit about how they must be killed in sequential order. We’re also a bit curious about the evil creatures (a.k.a. Mogadorians) that are hunting Number Four and his kind – even if, from a distance, they kind of look like Nero from Star Trek crossed with Lord Voldemort.

Dreamworks is clearly hoping that I Am Number Four will be the first installment in a new book-turned-successful film franchise. The pic will largely have the playing field to itself when it hits regular and IMAX theaters in the U.S. on February 18th, 2011, so it could do solid business at the box office.

How does I Am Number Four look to you?