"If They Came To Hear Me Beg" from Halo: Reach.
You have to do a running jump off a hundred-foot cliff and break your fall by assassinating an enemy. Aside from your inability to maneuver in mid-air, you can't be seen during the drop, the enemy has to be facing in precisely the right direction, you have to hit at just the right time and angle, the enemies are constantly moving about, and it sometimes doesn't give you the achievement anyways even when you pull it off correctly. It mostly just boils down to luck. So frustrating, but so satisfying to get after a few screen dents.
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All of the online achievements for the Duke Nukem 3D XBLA release are impossible to get.
Because absolutely nobody plays that game online.
You have to do a running jump off a hundred-foot cliff and break your fall by assassinating an enemy. Aside from your inability to maneuver in mid-air, you can't be seen during the drop, the enemy has to be facing in precisely the right direction, you have to hit at just the right time and angle, the enemies are constantly moving about, and it sometimes doesn't give you the achievement anyways even when you pull it off correctly. It mostly just boils down to luck. So frustrating, but so satisfying to get after a few screen dents.
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All of the online achievements for the Duke Nukem 3D XBLA release are impossible to get.
Because absolutely nobody plays that game online.