MineRalph is a really fun, simple and very challenging game that brings back memories of Super Meat Boy and Sonic - I'd definitely recommend it to anyone looking for a platformer challenge! Also, I think it would work great on mobile devices!
I was lucky enough to get a very special version from the developers, to use in my Let's Play video - they made a secret ending for me (if I could find it), one which I didn't expect at all! xD
You can watch it yourself in the video below :)