So I played as the Tube Subject.

Of course, I named my guy 'Subject 001'.

001 died from bleeding to death shortly after figuring out he had to smash the glass.

The next attempt was named Subject 002. You probably see where this is going now.
002 died shortly after breaking out of the tube from the zombies that promptly smashed open the door and tore him to pieces.

003-010 all died similar deaths, and never made it out of the hallway.

However, 011 was different. He was... let's say, smarter than the others, with a bit of luck. After suffering only a scratch on the forearm from the glass, he managed to lure a single zombie inside the room and killed it, stealing its clothes both for protection and to stop his bleeding. He promptly escaped to the vents, and after some scuffle lured in the rest of the zombies two/three at a time and then stomped in their heads. A good deal of them wore military clothing, and even a few backpacks. However there were no supplies or weapons - for a good two days 011 had to use his wits and his bare hands to stay alive.

The major breakthrough was when 011 mustered up the courage to go back out into the hallway, praying there were few enough zombies for him to go unnoticed. His prayers were unanswered the first time. A hasty retreat led to yet another battle for survival as 011 dispatched dozens of zombies with his bare hands. A tiny ray of light did shine on 011, however - one of the zombies' bags contained some food and water. It kept 011 from dying of thirst.

The second prayer was answered in turn - 011 quickly crossed the hallway and made it into another set of vents. This led him to some sort of medical area - there were other paths, but there were too many zombies banging on the vent cover to even attempt to exit that way. 011 exchanged his dirty rags for proper bandages, dragged a chair from the room into the vent and fell asleep with the help of painkillers, antidepressants and sleeping tablets.

011 woke up after a few hours of slumber, still tired but incredibly dehydrated. In a last resort venture, he sneaked down the hallway to an office area where to his delight, he found a water dispenser. He only managed to get a few sips to quench his thirst before he was discovered by a group of zombies and had to retreat once more. Bruised and batted, but not broken, 011 had somewhat better sleep that night thanks to the water.

The next day 011 was determined to get more water and a proper weapon - this entire time the only thing he had found was a measly screwdriver, which was also about to fall apart. 011 stealthily made it back to the water dispenser and managed to fill a bottle of water, and then managed to dispatch the zombies from before quietly. He went up the stairs in the hallway, which led to a small storage area filled with crates. This was where 011 found his first weapon - a shovel. A simple tool designed to aid those who wished to carve the soil - now in 011's hands, it was a tool to carve a path through the endless hordes of zombies.

The shovel served 011 well. What was once a group to retreat from, was now a mere nuisance. As long as 011 kept his back clear of enemies and his shovel smashing into skulls, he was able to press on. And press on he did, up flights of stairs and down sets of hallways - until he found a security post. The guards were long dead, the door was smashed open - but most importantly, the armory was intact. After barricading himself with several metal cabinets, 011 fell asleep in the security post, deciding to check the weapons after waking.

The armory proved to contain ample supplies, offering 011 a wide plethora of firearms. 011 chose a shotgun and a pistol, taking all the ammo he could for both. With the shotgun on his sling, the pistol on a holster, 011 kept moving with his trusty shovel in hand.

Eventually 011 reached what seemed to be a subway station of sorts. The train was nowhere to be found, but the tracks were intact. 011, in an attempt to walk along them, tripped and fell through the rails onto the ground below. Luckily he was uninjured, and 011 kept walking. He reached a set of stairs which allowed him to reach the surface again, and he realized that he was in a transport area. Several container cars and dozens of storage shelves littered the large room he was in. And of course, there were the zombies. Too many zombies, to be exact. 011 already knew he had nowhere to retreat anymore - the fall from the tracks was a one-way trip. Readying his shotgun, he fired at the nearest infected.

100 shells and dozens of dead zombies later, 011 was beginning to regret his choices. No matter how many he killed, more took their place. It was getting harder and harder to avoid getting grabbed by ducking and weaving through the shelves. But at last he saw an opening - momentarily, there were no zombies coming through the door which read 'EXIT' over it. He dashed through, nearly getting tripped by a crawling zombie - and was met with a horde larger than ever before.

011 ran. He ran and ran, occasionally firing a shot or two behind him just to slow the horde down as much as he could. Eventually even that became a futile act as they started coming from his front, forcing him to focus solely on running through them. But finally, he saw light - actual sunlight. It must be the exit, it must be! Escape was so close!

And then as 011 finally made it through the main entrance of the facility, he realized with absolute horror - that method of access to this facility was by helicopter. He was standing on a helipad, not a road. And there were no helicopters here.

011 turned and raised his shotgun, facing the approaching horde.

He knew there were more of them than he had bullets. He knew they could throw more bodies at him than he could throw blows with his shovel. He knew it was truly hopeless.

But, damned as he was, he wasn't going down without a fight.

011 screamed a battle cry, and fired.