A story about a smartphone giving the main character tasks and get money after completion.

I read this book a long time ago, and was not the owner of it. Someone found a phone, and the phone shows some tasks. When the person completes the task, they get money. The task starts with easy ones. As the main character complete more tasks, the tasks become more harmful to other people but gives better rewards. I think it becomes more life threatening as times go. That's all I remember. It's maybe a trilogy if I'm not mistaken, and I only had read the first book. I think I read it around 2015/2016.

Edit: I forgot to mention that the protagonist found the phone. He/she was not the initial owner of it.

What's that book?: Game by Anders De La Motte