It's an action-clicker game called One Million Skeletons, and the goal is to kill all one million skeletons.
In One Million Skeletons, you have to help the hero beat the huge number of monsters. You can hurt the skeletons by clicking on them, or you can hire new heroes to help you with this impossible task.
You'll start with one hero, and you'll need to earn money to improve them or hire new ones. You can also improve your skill by making it do more damage with clicks, or you can train your hero to get better. Get a shooter and a priest to help you on your quest, and try to kill every skeleton that comes your way.
Have fun and good luck!