Playing Remission 2 gives you an idea of what goes on in the body.  It gives you an idea however that is not exactly what takes place.  Our body has cells in which attacks the foreign invading cells because they do not belong in or around our body.  In this game Remission 2, you are controlling a character who is flying and moving about on the top of the screen whose objective is to defeat the invading enemies.  These enemies cannot reach the top of the screen where the flying character.  Basically you have 6 to 7 different weapons which allows you to defeat these enemies.  How you use utilize these weapons defines your character because there are different ways to approach this just like to skin a cat.  After the second or third level you should fully grasp this game and prepared to take on the next few hard levels with confidence.