"It's a mess, sir. We're scattered all over this valley. We called for evac, but until you showed up, I thought we were cooked."
Ok i have 2 for Campaign and 2 for Multiplayer, i might make a few later on.
Campaign:
"Lie & Denial" 30GS: Kill every ally until you get to Captain Keyes on the level Truth and Reconciliation.
"Tunnels, Aliens, One Gun" 60GS: On the level Silent Cartographer, Starting at "Shafted" part where you go underground to search for the Cartographer, use of only one weapon with its own ammo, and kill every enemy, on any difficulty.
Multiplayer:
"What's a Killtrocity?" 20GS: Get 2 Killactulars in a row, in a Slayer or CTF game on any map.
"Wait were not on the moon?!" 10GS: Make your Warthog jump over a Scorpion tank or Ghost.
I mighty be making more soon, come to check back in a few days!