You can play with Koans online: https://play.kotlinlang.org/koans/overview.
You can solve the tasks right inside IntelliJ IDEA or Android Studio by installing the EduTools plugin and choosing Kotlin Koans course.
Here you can find all the challenges done and ready together with the explanation of each task and example.
Go ahead and use the latest IntelliJ it have the setup for the project to run single examples
Feel free to use. If you can add me to any credits would appreciate it. Thanks.