The Top Ten Most Challenging Xbox 360 Achievements of All Time (So Far)

Acht -- 08: Left 4 Dead "What Are You Trying to Prove?" (35 G)

Required Action: Survive all campaigns on Expert.

While there used to be a dashboard glitch that could be used to make unlocking this very tough Achievement easier, that was patched -- and considering that any gamer looking to unlock this one will be committing to an average of 3 hours per campaign... While this one nominally might qualify as a "putting the time in" type, the frustration levels it has generated on the chat boards wins it the 8th place in our countdown.

Further complicating the process, while gamers can do the campaigns out of order if they choose to, they must start each campaign from the start (the opening pan-in) and complete each to the finish (closing pan-out) in one play session *while connected to the Internet* to the point at which the game acknowledges that "The Survivors have escaped." Dropping your 'net connection during play can (has) caused the game to not include the session as a completed play-through on Expert.

With a total of four campaigns to complete, this will likely take a cumulative total of around 10 to 12 hours to unlock, so it is no wonder that only an average of 12% of the gamers who play this game have unlocked this Achievement!