Valve has collected and released the Achievement statistics
for its cooperative, zombie extermination-fest, Left 4 Dead
. The most frequently unlocked award amongst Steam users is "Drag and Drop," with 72.6% of players having earned it after splattering a spluttering Smoker zombie before it managed to inflict damage on a fellow survivor. That's sticking to the spirit of the game!
Unsurprisingly, nobody's managed to kill 53,595 Infected (yet!) and only 0.2% of players have survived every single campaign on Expert difficulty. That's the one where the AI Director puts a paperweight on the "Spawn Tank" button.