Cuzzle by GalacticThumb FREE

Cuzzle is a sokoban type puzzle app game. The object is to push the white cubes onto their targets, then get Your Man, the red cube, onto its target. (Sometimes Your Man is blue.)

Elements
1. Some squares can only be traversed once.
2. Wormholes. Not sure if I've seen this feature in a sokoban game before.
3. Landing on a solid white square (on the harder levels) causes new black cubes to appear.

There are 90 levels. They are challenging, but not impossible.

There are over 50,000 players on the Leaderboard! Only 1 person has done all 90.  A slew of people have done 89 levels.  I've done about 50 levels.

https://itunes.apple.com/us/app/cuzzle/id1185407542?mt=8

Other Good Sokoban Puzzles
A Good Snowman is Hard to Build Charming
Go to Gold - superb
Go to Gold 2 - I hope a third version comes out.
Pepe Porcupine
Sokoban Cargo
Push Box Sokoban
Push Around
Boxed In - loved this. First in a series of 4.
Pengu Push
BoxWorld - awesome. I still remember struggling through levels 26 and 35 for days.
Fireman Arcade
Paper & Light
Square Push Square
Professor Max
Puzzling Cubes
DJ Mole
Sokoban Evolution 
Test Chamber - brilliant
Duck Roll surprisingly very good
Color Labyrinth - excellent