Stormpiercer

You're one of the last soldiers of your country, and you somehow find yourself deep behind enemy lines. So deep, you've infiltrated their base. The vast majority of their forces are in this base, and it has an obscure flaw that you just so happen to have the means to exploit. You've a special revolver that packs several punches, but you only have 6 rounds left. You need to make it to the flaw before you run out of bullets and escape to give your country any hope for survival.