Touch Zombies In Circle

This game's goal is to destroy many zombie as many as possible by touching zombies in circle.
Here and there zombies come.
Zombies are in circle.
The point is that touch zombies in fast speed before this circle goes smaller.
You can keep circle size by touh the place where many zombies reside together.
If circle goes smaller and disappears then game will be over.
Must touch zombies in circle before circle goes smaller and disappears.
Win a victory by destroying zombies.
Compare your score with other's in global leaderboard.