Since "free" downloads from unofficial sites often come with malware or viruses, here are the safest ways to play:
These are official, free "mini-games" that use the 2.11/2.2 engines and offer unique levels not found in the main game.
This is the official free version by RobTop. It includes many of the 2.11 features and several main levels. It is the safest way to play on mobile without spending money.

