Well, there is a way to play it for free on a PC. At least if you have it on Android phone. Maybe on iOS too, if there are iOS emulators?
You can install emulator on PC, and if you use same account on emulator, you will be able to play it on PC. It's not as good as native PC version (keyboard control, a bit wider view area, etc...), but it's playable. Before we had PC version, I played it on Android emulator.