Shoot, upgrade, conquer enemies, defeat bosses, acquire achievements, collect gems, all in an attempt to save yourself and your gun from the clutches of the evil Professor.
You begin by finding yourself stuck at the bottom of a cave with no idea how you got there. Befriending the first thing you see, an intelligent gun, you begin your ascent to freedom.
Control your character with AD or Arrow Keys, jump with W/Space/Up, and use the mouse to aim and shoot (or switch control schemes in the options). As you acquire more guns, use QE or 1-4 or the mouse wheel to switch between them.