Warner Bros. may be following in the (very large) footsteps of Electronic Arts and THQ when it comes to discouraging -- or at least profiting from -- the sale of used games. Joystiq has learned from a tipster that when Mortal Kombat hits shelves on April 19, its box will include an "online pass" token that must be redeemed before playing online. At present, WBIE evidently intends to do the same for its high-profile releases F.E.A.R. 3 and Batman: Arkham City. Since the latter won't feature multiplayer, though, the token would have to unlock some other (equally attractive) content.

According to an email obtained from our source, which appears intended for retailers, WBIE won't be promoting the pass -- in fact, no reference to it will appear on the game's packaging. Instead, it is apparently providing retailers with details on the pass, including how to purchase a new one if you're buying a used copy of the game. Unsurprisingly, a new pass will run 800 Microsoft Points / $10 for Xbox 360 and PS3, respectively. We've contacted WBIE for comment on this information. You can find an excerpt from the retailer email past the break.