Vaxine

From Mobygames:
In this first person driver/shooter, the player must protect a body's base cells from attack by evil infecting cells. The field of battle is a toroidal grid on which your tri-colored half-sphere base cells sit awaiting your protection. The invading cells (also tri-colored spheres) attempt to bond together into groups and destroy your bases. You destroy the infecting cells by lobbing antibodies (also tri-colored spheres) at them. Hit an infector with the right color shot and it is destroyed. The catch is that you have a limited amount of each color of ammunition. Run out of a color and the game is over. The situation is also complicated by Spitters, enemies that appear and spew out new attacking cells if you take too long to complete a level.