It's a challenging tower defense game thingie with a dash of bacteria thrown in just for fun! Ur objective is to stop the microbes from getting through to ur delicious food. It may sound simple, but it's not. These microbes are a hardy lot and require targeted shooting to eliminate them.
Pick up ur trusty bow tower thingies, something every microbe fighter needs, place them, and set 'em up to kill whatever microbes come their way.
Be aware, u need to select which colored microbes ur towers can attack. E.g. a tower that is set to red, will only kill red microbes. Of course u can set ur tower to kill various colored microbes, but it costs. So be selective and use only the colors needed in any given level.
Also, remember u can upgrade ur tower shooting speed and range and there are super attack buttons that u can use once they are charged up.
Be prepared to fail before you win. It takes a bit of getting used to and fast thinking to get through this game.