I really liked the idle concept of the game, and the art is very good!
A few important points for me to note:
*The colision between the red ones and the green ones is a little strange and lot of times the red just passed through greens and did nothing to them.
*More upgrades would make the game even better.
*The game has the potential to become a crazy idle experience with tons of objects that destroy the massive amounts of mutants on screen, but even after buying all the different types of objects that kill the mutants, the game still felt slow.
Cool game overall!