I'll post mine later as I'm still trying to assemble a list.

(Left 4 Dead)  Nothing Special - Survive a campaign with no Survivors taking damage from Special Infected.

The only one I can think off

(Gears of War) Seriously - 10,000 kills in multiplayer.

That achievement took forever!! Not to mention it dosnt track like 30% of your klls.

 yeah thats true, but regardless its still my hardest achievement and probably one of the hardest/ time consuming single achievements on any game to date!

Cod WaW Heart of the reich

zombie genocider , and all agility orbs, before the sound update

On Veteran.....yes lol. That was a nightmare getting it, like 10 grenades surrouding you all the time.

I struggles with 'the sum of all zeros' too

Zombie Genocidest
Kill 53,595 Infected.

I am still long way to there.

• - Should Be Autographs!
  Signed off! Awarded for completing all 24 Signature Takedowns! - Burnout Revenge
• - Own Worst Enemy
  Got a Gold Medal with all Debuff Skulls Active - Halo Wars
• - Untouchables
  No Survivors take damage after contacting the rescue vehicle. - Left 4 Dead
• - Historian
  The player has found every audio diary. - Bioshock
• - You Got The Message
  You delivered all 30 cars ordered through text message. - GTAIV
  

thats the one from left4dead thats one more kill then the dead rising one right? man im working on that one right now... you are right the dead rising one is easier to get then left4dead one .... I can only imagine what deadrising 2s will be the 53,594 was supposed to be the population of the town..... vegas has shittones more people then that