It's a nightmare. You are trapped in an abandoned mine with an injured comrade at your side against God-knows-what. Make your stand, get out alive. Three words of advice: shoot to kill. These things are not human, they are monsters..
As an experienced sniper, you have successfully managed to penetrate into enemy territory. Now it's up to you to eliminate all of your foes, causing confusion amidst their lines, thus helping your fellow soldiers to survive the enemy threat.