Records of the Flycatcher

... When you finally regain consciousness, you find yourself lying face down in the snow, with a long trail of footprints behind you. It seems you had collapsed from exhaustion.
  You find yourself struggling to flip yourself over. When you eventually do, you find several newly acquired cuts and bruises all over yourself. You quickly administer some first aid, before spending a few minutes fiddling with your radio set. But as you expect, your frequencies remain silent.
  On your back lies a small saving grace: a state-of-the-art imported bolt action sniper rifle, far superior to any domestically manufactured equivalent. You forgot exactly how it fell into your hands in the midst of the chaotic rout. And despite everything, part of you wished its previous owner was still alive.
  Your chain of command has completely broken down. Hadrian soldiers are pouring across the eastern border in their tens of thousands, and you are one of the last few things standing between them and the defenseless villages across the vast Altheimian wilderness. In the absence of further orders, you have no choice but to conduct a fighting retreat by yourself.

Quietly eliminiate Hadrian officers and agents. Set up ambushes, plan your attacks, and do everything in your power to slow down the enemy advance.

Navigate through the vast Altheimian wilderness, trudging through terrain that may aid or hinder you. Encounter the occasional wildlife curious enough to approach your bonfire.

Rendezvous with fellow soldiers. Exchange intel, or assist them if they are in trouble. Deal with any who had stepped out of line. 

Encounter fellow Altheimians, resupply and rest in friendly villages, purchase their goods and services if needed. Help any remaining civilians flee the oncoming Hadrian onslaught, or ignore them to focus on your objectives. 

Find abandoned items within the war-torn ruins that scatter the wilderness, and try not to get drunk from any leftover alcohol you find. 

Try to balance your Sanity and personal well-being with the realities and necessities of war.