OMG, the bosses! I always run through a game like this solo, so I can fully appreciate the story and exploration. The boss is always just a dude with a flamethrower that one-shots me who is always sprinting at me and takes all of my ammo to get his shield down. I swear that has been my last three boss fights. The only saving grace is that they don't lock any doors behind you, so I can run backwards through the whole level slowly whittling the boss's health. It also saves you from the axe guy who magically appears only when you aim down sights. Those mechanics have no staying power.