I got this achievement sometime last year and is probably my most prized achievement, it's the "Hardcore" Achievement from Fallout New Vegas. It's basically playing the game on Hardcore mode from start to finish, where you actually get hungry, dehydrated, sleepy, tired, ammo is scarce, health doesn't regenerate, easily irradiated, etc. It was a long and frustrating road but in the end i was happy to get it!