This mission. I breeze through the first part, having killed all the bloodsuckers in Krug Antenna Complex before starting the mission, and figuring out they don't respawn after several minutes of "Nothing is Scarier". Then I go get a canister of poison gas, which is on a bridge within sight of some Mercenaries with seriously good aim, and an endless supply of bullets. Okay, after trying to fight them once and failing, I sneak in, and run like hell when I get the gas. Then I need to go hook up the canister to the ventilation at Krug. No problem. Hook up the can, turn valve, wait for gas to take effect. And what do I hear? A bloodsucker scream. The kind that says "Oh hey, a tasty looking human. Imma go suck his blood." And two of them rush me. Now, I've killed bloodsuckers before, but that was when I had both the element of surprise, and enclosed spaces with grenades. This is open space, they both see me, and I've got a Saiga and the same armor I started the game in, minus about 80% durability. Die, reload. Rinse, repeat. God, I hate this game sometimes. But dammit, it's so goddamn satisfying when you stand before the Swiss-cheesed remains of two bloodsuckers. Then I die to flesh on the way back to Sakadovsk, because that took all of my healing items. Such is the Zone. At least I got enough cash to upgrade my gear after that.
STALKER: Call of Pripyat, MISERY 2.1 mod. Got a serious love/hate relationship with this mod.