Looks like GameStop marketing has accidentally revealed yet another unannounced title, this time Ubisoft's Assassin's Creed: Brotherhood.

Brotherhood appears to be the multiplayer Assassin's Creed title Ubisoft had previously announced for a fall release. The back of the box says players can "Live and breathe as Ezio, a now legendary master assassin, in his struggle to strike at the heart of the enemy, Rome."

"And for the first time, take part in an innovative multiplayer layer allowing you to embody an assassin of your choosing and define their killing style," it continues, before calling it a "never-before-seen online multiplayer experience." A pre-order bonus, a character for the game's multiplayer component, is also revealed.

The promotional art lists the title for Xbox 360, PlayStation 3, and PC. There's even a first look at in-game screenshots; we'll update as soon as we get a scan for a closer look.

[Update: Just added a high quality scan of the promotional material, which includes a closer look at the game's art and two screenshots assumed to be from the unannounced title.]