Shoot your way through a zombie infected bio-research facility and find out what went wrong.
To pass through each room, pick up a keycard then exit through the door on top. Use arrow keys or W,A,S,D to move your player. Aim/turn with mouse / Left click to shoot / Hold left mouse button for continuous fire. Available weapons are listed at the bottom; press key #2 to switch to a sonic shell, key #3 for shockwave key #1 to load standard ammo.
A context menu should be shown when right-clicking or, on touch devices, long-pressing in the game. This menu especially allows to play in full screen and control the volume.