de Blob is a 3D platformer where players maneuver their hero, de Blob. Equal parts amorphous blob of paint, struggling artist, revolutionary and juvenile delinquent, de Blob's goal is to replace the drab, lifeless gray coloring that the I. N. K. T. Corporation has imposed on Chroma City and its inhabitants, the Raydians, with a range of vibrant life-giving colors, all the while avoiding and battling the gray-clad forces of the Inkies.

Chroma City was once a lively, vibrant metropolis bursting with color and home to its cheerful, diverse citizens, the Raydians. That joyful existence is shattered when the sinister INKT Corporation, an alien corporate military dictatorship led by the villainous Comrade Black, launches a sudden invasion as part of its ruthless War on Colour. Chroma City swiftly falls to INKT's army of Inkies and color-draining Leechbots, leaving the once-radiant landscape barren and gray. The captured citizens are stripped of their color and imprisoned as drab, joyless Graydians. Watching the takeover unfold from his distant jungle retreat, the heroic and endlessly bouncy Blob springs into action. Rescuing the last pocket of resistance, a plucky band called the Colour Underground, Blob joins their cause and sets out to splash color back across the city and free his people.