Great game. One of my favourites. Spending lots of time with it. However, and here we go, it’s relatively cheap to play until roughly level 50, from there onwards, the resources you need are so much, that spending real $$ can’t be avoided. Unless you want to wait forever to level your heroes. So yes, it can be played for free, but your progress will be painstakingly slow. Hence four stars. Five, if the resources requirements come down a bit, but that would hurt the business model, so I doubt it will happen.