i gotta say mine was the "splatter spree" acheivement in halo 3, because i tried for so long to get it, gave up, and proceeded to get it by accident.as well as finally getting my katana.
mine is the thnks for the memories achivement on gears of war two. It wasn't that hard to get but the fun i had getting it made me the proudest man in america because of the co-op freind i was playing with. actully it was the night befor new years eve so it was close to 2009. The achivement is not what i'm proud of it's the memories that it carry
I'd have to say beating Gears of War 2 on the hardest difficulty. Especially since I opened the package, popped in the disc, new game, and I went straight to the hardest difficulty. Oh, and I never played Gears 2.
Mine was definitely earning the Two for One on Halow 3...i was detirmined not to cheat or ask for help or do the chinese thing, even though all my friends had the achievement cuz of it.....and then....one fateful day...on a Lone Wolves slayer match....had a laser...aimed at one guy....another one popped out...BOOM....and just like that, the hardest achievement in Halo was mine XD...and after i got it, i didn't care about the winning the game, i was so happy haha
My greatest Acheivment would be either my 4 halo 3 gold skulls, or SPOILER ALERT! Defeated Atlas in Bioshock, the game that said "IN YOUR FACE, HALO!" yes, i said it. Bioshock owned all 3 Halos in one game. Sorry, Bungie. Good try.