Your objective is not to die!
You can drag and throw around everything, except for the green and black bacteria.
White cells can destroy the Bacteria, so try to hit them with one.
Gray cells can destroy the Bacteria, if you hit Bacteria hard enough with them.
Each Red Cell which reaches the exit gives you points.
Each Blue Cell which reaches the exit gives you a White Cell.
Bacteria can multiply if it eats Red Cells or reaches the Exit, so kill them fast!