In the months running up to Star Wars: The Old Republic's 2011 release, excitement for the MMORPG reached critical levels. It was, after all, essentially a massively multiplayer online version of the much-loved Knights of the Old Republic games, and one of the most expensive titles ever made.

While the combination of BioWare, LucasArts, and Electronic Arts produced a game that gained overwhelmingly positive reviews when launched, it didn't boast the lasting appeal of MMOs such as World of Warcraft. Less than a year after release, subscriber numbers fell below one million.

The drop prompted EA to move to a free-to-play model, though anyone wishing to stick with the paid-for option receives various bonuses and rewards. The decision paid off; new and former players joined the game, and two years later SW: TOR had more than one million monthly players once again.

Some will tell you that it's the game's series of brilliant CGI trailers that attracted them to The Old Republic. And with its upcoming Knights of the Eternal Throne expansion, we have one of the best yet.

The six-minute long video, titled 'Betrayed,' shows how the dark side of the force corrupts those who use it. Even if you've never played SW: TOR, it's worth watching the entire trailer - it's extremely cool.

The expansion puts players in the boots of the Outlander, a veteran of the Great Galatic War. You can influence the galaxy for the light or dark side of the force, based on your decisions and actions.

Knights of the Eternal Throne releases on December 2 for free to SW: TOR subscribers only. You can try the MMO for free here.