For me it was Mass Effect. It was not hard to do, but it sure was time consuming. What about everyone else?
What was the hardest game that you got all of the achievements in
Final Fantasy 13, Bionic Commando, Bioshock, Bayonetta, and BlazBlue are probably the one's I'm most proud of.
Rise of the Argonauts and The Force Unleashed were bitches too.
Overall though FFXIII was the one I had the most fun getting the S-rank with. Man I love that game.
Forza 3 has a achievement to win every single race in the game, theres gotta be like 500 individual races. Not exactly 'hard' but very time comsuming, probably over 60 hours.
I've almost got all the Dragon Age achievements, again, not 'hard' just time consuming.
I guess the hardest would be like a game that has MP achievements, like Gears of War 2. I hate the MP, so I'll never get those achievements.
It's before the time of achievements/trophies, but I completed Devil May Cry 3 on all difficulty settings (well, you do get S-ranks and unlockables n'stuff, so it's sorta achievement-y). Beating Vergil finally after a 20 minute battle (no joke) on Dante Must Die was one of the hardest things I've ever done in a game, and the most satisfying (as a side, great ending too).
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