It was fun playing the first 3 levels but it's impossible to play without buying coins. Not like you buy coins to help with hard levels, but as in you buy coins otherwise you can't complete a level. I'm only on Level 5 and it already sucks. Point in case: each time you hire a doctor, they start with Level 1 Healing, no matter how far into the game you already are. Which means you need to upgrade the new doctor's Healing in order to make them move as fast as the other doctors you have.