Back in the ancient days of the Xbox 360, I really enjoyed Xbox achievements. I spent way more time than I care to admit trying to lock down every single achievement in Left 4 Dead.
I used exploits to assist in beating Expert, I changed the difficulty to Easy to farm massive numbers of zombies to kill, and all sorts of tactics to nail down all available 1,000 gamer points.
There was once a night where I managed to wrangle together seven other people, and we played a patsy of a 4v4 game, where we all took turns trying to farm down achievements, such as the one that involved puking on all four survivors simultaneously, one special infected incapacitating all four survivors, and so forth.