KenzS said:
Beat the Epilogue on Call of Duty 4 on veteran..... IMPOSSIBLE!
Got it, not terribly hard. It requires timing and precision movements. If you go to the wrong place or move just a little too early or late you're screwed. The level is just aggravating. Keep trying, it'll happen.
Other people may say Two for One on Halo 3. That on is a bit difficult merely because everyone wants the splaser. If you do get it, all that needs to be done is find someone stealing a vehicle or two people fighting. Line 'em up, and its gold.
I'd have to say that the most difficult one for me was 100 headshots on Gears of War. I fought so hard for that sniper (and I was actually good with it) and then had to get 100 headshots. Problem was, the achievements were bugged... I didn't actually get the achievement until I had well over 270 headshots with the sniper (I kept track of all kills with all achievement guns, I still only have 18 with the boomshot).