The mobile app is centralized and runs off a twin algorithm that emits coins from the blockchain at approximately the same rate as the full miners based on a CPU benchmark of the phone. This allows the phone to run without getting hot and without using tons of power and bandwidth that previous attempts at phone mining have needed. But remember, they are not bringing blockchain utility, they are bringing a different utility - they are bringing on users at a ridiculously low CPA, and allowing Electroneum to have viral growth.
It also suggest the users to that they download and run the full miner(PC Mining) if you have facility to do so, enabling the growth of the cryptocurrency's infrastructure