You wakeup to discover yourself lying in a cold, dark wet alley, having a massive hangover. In hindsight, the combination of medical alcohol and the punchbowl at the latest NG party might not have been such a great idea after all.
Failing to stand up you decide to curl up into a ball and go back to sleep when a huge roar awakens you. Realizing that this was the same noise that woke you up initially, you draw the ONLY logical conclusion -- Someone must have fed some newbs after midnight, got them wet and thereby causing the inevitable zombie invasion.
Adrenaline pumping you look around for some way to defend yourself and find that you are still carrying your trusty gun. "HAH who is laughing now" you think while pulling yourself up. You load the infinite ammo pack, take up your favorite defense stance and get ready to fight.
Use WASD to navigate the screen
Use mouse to aim and shoot
1-4 changes weapon
You can buy upgrades and more ammo by clicking the $ signs on the right and left side!