The game over concerns the end of one round in the Bioconsole game.
Indeed, you can not play indefinitely with the Bioconsole, and as every funny game something can happen to the hero! Here, the end of the game is the death of the bacteria.

As you know, the goal of the game is simple: to allow BACT'Man to survive as long as possible. Stop him from getting in contact with the virtual lasers that will appear faster and faster as the game goes on. If BACT'Man were to be touched, a bright flash will appear at the microscope and will activate the liposomes opening. The toxins will eliminate our hero that will lose his fluorescence ... GAME OVER