You are a predatory fish and must eat the little diatoms to survive. But, they seem to be adapting. Maybe you can keep them under conrol somehow?
This is a small experimental game I originally made for Ludum Dare 24 (originally named "Barnacles"). It was made in MMF and uses a genetic algorithm to handle breeding the diatoms. I've added some polish to the version I made in around 24 hours, including a "boss" mode and online high score chart.