Android doesn't need one. Stock Android has had bluetooth controller suport for a long long time. No need to hack the phone / tablet. Even many games that don't suport joypads actuially do work with them such as the Sonic titles. Makes playing the games so much better.
I downloaded this the other day and its work is as fantastic as the sonic cd port maybe even better. Playing it on my iphone 5s and it looks beautiful. Also if you have a 3ds I recommend trying out m2's sonic 1 3d port, it looks nice and has a lot neat options.
I know that lol, im playing on ouya so i only have the touchpad on the ouya controller so its almost impossible to do that on time, there was also a button code for the sonic 1 re-release level select, just wondering if anyone had found one for 2
The code for Sonic 2 is the same as sonic 1 for android and ios and has been mentioned at least twice in this thread.